Because high-end laptops alone don't scream "I'm stinkin' rich!"
I'd build a big tall house with rooms by the dozen, Right in the middle of the town. A fine tin roof with real wooden floors below. There would be one long staircase just going up, And one even longer coming down, And one more leading nowhere, just for show — Fiddler on the Roof, "If I Were a Rich Man"
In a nutshell, conspicuous consumption is any extravagant spending that has no real purpose other than just to show off someone's wealth. Sometimes this leads to a vicious cycle of "keeping up with the Joneses", when two people or families each feel that they need to buy more things to show they're just as wealthy as the other, sometimes going Up to Eleven.
Anyway you look at it, these people are just spending money for the hell of it. You aren't buying a luxury car. You're buying a gold plated one. You don't just have a private jet. You have a private aircraft carrier (and not for your private army either).
Yes, there can be at least somewhat understandable reasons to spend a lot of money. If you see an expenditure for a reason like these, it's not this trope:
Sometimes it's just a bigger and better version of a thing we need anyway. We need a car, and they buy luxury cars.
Sometimes it's expected, or even required, for cultural reasons. Ermine Cape Effect mentions it wouldn't do for royalty to dress like slobs.
Sometimes what these people do actually requires a large expense. A CEO of a multinational corporation often deals with people who just need to be spoken to in person, so he/she needs a private jet to accomplish that.
In Mobile Suit Gundam Wing, Dorothy Catalonia seem to have a thing for gold-plated vehicles: a limousine, a space shuttle and a truck.
In Speed Grapher, there was a Euphoric who literally eats diamonds. If she eats enough, she becomes a walking, talking diamond.
Comic Books
Richie Rich had gold-plated, gem-studded everything. Conspicuous Consumption is the only joke in his comics: mundane gadgets festooned with precious metals and minerals, landscaping feature like hedges and swimming pools shaped like dollar signs, the immense size of the Rich estate (requiring multiple ZIP codes, needing its own transit system), and so on, ad nauseum.
In Ocean's 13, Al Pacino's character receives a gold plated and diamond encrusted cell phone as a gift. He's obviously been desiring one for a while.
A long sequence in Apocalypto highlights the conspicuous consumption of the Mayan royalty to construct their ostentatious buildings. The damage this causes to the environment and their peasants is shown to be terrible. The nobility is also shown to be covered practically from head to toe in jade jewelry. In the DVD commentary, director Mel Gibson uses the name of the trope frequently to point out his thinly-veiled commentary on modern society.
The buildings, at least, are Truth In Movies. The Mayan city-building culture almost certainly fell due to deforestation (to provide the fuel to make the plaster for the ornately decorated buildings) becoming so extensive that it altered regional rainfall patterns, leading to drought, agricultural failure, and systemic collapse.
The title characters in Fun With Dick And Jane are very much concerned with what the neighbors think — and what the neighbors think is that it's best to show off one's wealth. This intersects brutally with their poverty.
Melancholia features an extravagant wedding at a castle as the world ends. The director actually contacted a wedding planning service and let them go wild.
Casino: Expected since it takes place in Las Vegas, but especially anything to do with Ginger, from her clothes and her furs to her Big Fancy House and her vault full of jewels.
Literature
Older Than Feudalism example - in the ancient Hindu epic, the Ramayana, several entire chapters are devoted to explaining the over-the-top splendor of Ravana's palace, of which everything constructed is constructed of rare metals and stones, and everything natural (i.e. gardens) is of only the finest, purest quality.
The Great Gatsby, which also deconstructs the American Dream and the Roaring Twenties into teeny, tiny pieces. Gatsby regularly throws the biggest parties just to show off, in hopes of attracting the attention of his childhood crush. In one notable scene, a guest enters his impressive library and wonders if the all books are fake. He examines them and sees that all of the books are quite real, but none of their pages have been cut. It's an entire library of unread books, just for show.
The Satyricon by Petronius, written in Roman times, is full of this. In the chapter describing banquet of Trimalchio, a heavy silver platter is dropped by one of the household slaves, and the wealthy Trimalchio commands that the platter be left on the floor and swept out with the rest of the garbage. Between courses, the guests have their fingers washed with wine instead of water. The narrators are obviously party-crashers, but no one cares.
Dark Future: There's a lot of this, with the cosmetic genetic enhancements offered by GenTech, including up to five implanted sets of teeth to replace your own as they wear out, but Gavin Mantle, winner of the ZBC Blotto Lotto prize of 100 million dollars goes on a spree of spending to live up to this including a gold-plated Rolls Royce shaped like a penis, a huge mansion shaped like a pair of breasts with a swimming pool the bottom of which is covered in gemstones and a small army of personal Sexbots turns the dial up a touch more.
In Charlie and the Chocolate Factory, Willy Wonka tells the story of how he helped an Indian prince build an entire castle out of chocolate. The prince sees the folly of his ways when the castle melts around him. When the movies were made, only the Johnny Depp version got to see this scene realized on film.
In Frederick Pohl's The Midas Plague, the US went through a period of severe shortages, which strongly inculcated a strong "thou shalt not waste" ethic in the population, followed by a period of cheap fusion energy, and automatic production, which created huge surpluses. But people couldn't "waste" things, so they had to consume them, which leads to an inversion of consumer culture, where "poor" people have higher consumption quotas that they have to meet.
Nobility in A Brothers Price tends towards to this, with expensive outfits that are only intended to be worn once.
In The Stars My Destination, (almost) everyone can teleport themselves, so the rich show off their wealth by "conspicuous transportation"—traveling the old-fashioned way. At one point a character arrives at a party by steam locomotive, on a track laid just for the occasion.
In Sewer Gas And Electric, a corporate executive prepares for his upcoming date by ordering, among other things, a $50,000 ten-pack of condoms.
Live Action TV
Interestingly averted by Star Trek's Ferengi. Their entire society is capitalism taken to the point of parody, but their profits seem to go mostly toward making more profit rather than getting wasted on ostentatious frivolities. Even the most obscenely wealthy Ferengi wear relatively modest clothing and only minimal bling. Although Ferengi occasionally engage in some form of debauchery, their vices are surprisingly minimal. In one episode of Deep Space Nine, Quark is amazed that humans would buy their own poison in the form of cigarettes.
On LOST, several characters, especially evil tycoon Charles Widmore, make a show of drinking the fictional MacCutcheon whiskey, a bottle of which costs several thousand dollars.
On Chappelle's Show, one MTV Cribs parody sketch had an insanely rich celebrity (Dave Chapelle himself) who ate dinosaur eggs and sprinkled diamonds on his food because it made his "doody twinkle".
In The Office Michael Scott manages to do this in the absence of actual wealth. When Oscar examined his finances to explain his debts he ended up dividing his spending into three categories, of which the third was the largest: Things that he needed, things that he didn't need, and things that no one, anywhere, ever needed.
Mystery Science Theater 3000 noted this in the short film Design for Dreaming, made in 1956 to advertise GM's Motorama expo. As the heroine and her man drive away in their fabulous Thunderbird II, Mike Nelson quips, "Conspicuous consumption makes our love stronger!"
On Parks and Recreation Tom and Jean Ralphio start their own entertainment company after Jean Ralphio gets a lot of money. They primarily spend the money on extravagant furniture and hire pro basketball players and beautiful women to just hang around the office (since nobody in the company is doing any actual work). They even give everyone who visits them a free iPad. Naturally the business fails.
On Downton Abbey Martha Levinson does a major one of these: if it's not the furs, then it's the pearls and jewelery; if it's none of the above, then it's the seriously posh car that is very posh for the time with white wheels (even Robert is impressed), and her "generous" income that proves it. This woman... is STINKING RICH!
Music
Billy Joel's Movin' Out (Anthony's Song) is a criticism of blue-collar and lower-middle class New Yorkers who are prepared to literally work themselves to death, in order to be seen to keep up with the Joneses.
Nickelback's "Rock Star" is one long ode to just what the singer's going to buy when he's successful.
"Gangnam Style", by Psy, is about out-of-control conspicuous consumption and overpriced coffee in Seoul's trendiest district.
Tabletop Games
Common in Exalted's Yu-Shan and Underworld; since the former has prayer form into a substance that can be formed into practically anything, and the latter has items used in burial rites carry over as idealised (and sometimes magical) versions of themselves (such as a wooden cart painted gold becoming a magnificent golden carriage), excessive and blatant luxury is the norm.
Le Bret(with the action of throwing a bag): How! The bag of crowns?...
Cyrano: Paternal bounty, in a day, thou'rt sped!
Le Bret: How live the next month?...
Cyrano: I have nothing left.
Le Bret: Folly! Cyrano: But what a graceful action! Think!
At Act II Scene I, We see Raguenaeu’s Bakery, where Ragueneau is giving free his pies to his friends, the starving poets… who in retribution give Ragueneau their poems and hear his own poetry (and they flatter him). Ragueneau buys a lyre made of pastry from one of his own apprentices, and when he shows it to his wife, Lisa, she lampshades that is a silly consumption. Also, when a multitude of invaders comes to his bakery at Act II scene VII and break all, he doesn’t ask them for paying the damages. This attitude explains why he is ruined at Act III.
Another Apprentice(also coming up with a tray covered by a napkin): Master, I bethought me erewhile of your tastes, and made this, which will
please you, I hope. (He uncovers the tray, and shows a large lyre made of pastry.)
Ragueneau(enchanted): A lyre!
The Apprentice: 'Tis of brioche pastry.
Ragueneau(touched): With conserved fruits.
The Apprentice: The strings, see, are of sugar.
Ragueneau(Giving him a coin): Go, drink my health!
(Seeing Lise enter): Hush! My wife. Bustle, pass on, and hide that money!
(To Lise, showing her the lyre, with a conscious look): Is it not beautiful?
In Team Fortress 2, a Heavy Weapons Guy achievement for eating 100 Sandviches references the trope, mixed with Funetik Aksent, as Konspicious Konsumption.
Grand Theft Auto IV parodies it with the in-game TV show "I'm Rich", including obvious parodies of people like Paris Hilton and others.
The Ballad of Gay Tony introduces Yusuf Amir, who spends his money on Bling Bling Bang, Hookers and Blow, and ridiculous vanity projects like building the tallest skycraper in Liberty City. Since he apparently has the money to buy anything, the only use he has for the player character is to steal "the things they won't sell him", like military hardware.
Pokey and Alloucious Minch's offices in the Monotoli building are made entirely of gold.
A lot of Simulation Games allow the player to purchase pointlessly expensive things because they can.
Tropico allows the player to build a play gold statue of yourself along with other such needless expenses while your people starve and live in ramshackle houses.
Webcomics
Both Ricci and his manager in Fite! sport solid gold jewelry once Ricci gets the belt.
In Commedia 2X00, Mr. Pants' family has been earning royalties on their patent on pants for centuries. His sidekick/attendant is a solid gold robot named Goodz. Several early updates are spent in his treasure room, which includes things like a Polybius arcade machine, the Chaos Emeralds, and an electric guitar autographed by Mozart.
An episode of Cracked's Does Not Compute deals with the Numi, a real life $6500 toilet that comes with a tablet PC to pick various settings like seat temperature, bidet control, and a selection of music. Yes, music, which was composed specifically for the Numi.
An Alvin and the Chipmunks episode had Simon develop a device that could look into possible futures. One was where the chipmunks and chipettes were incredibly wealthy. They bought their kids guitars made of diamonds, with ruby picks, and there were apparently emerald strings.
Some of Goldie Gold's has a few of these that aren't even gadgets, like a diamond studded nail clipper.
Similarly, Richie Richlived this trope. Fuel for thought comes when you contrast his typical attire of a sweater with the letter R on it (or a black jacket and shorts when he was younger) to his hyper-luxurious lifestyle. It's almost as if he's Zen'd past needing to display personal bling. One Robot Chicken skit plays with this, and mixes Richie with a black rapper stereotype.
He was past displaying bling on his person, but not otherwise. One bit was a jeweler leaving after repairing one of the phones. His normally-wealthed female friend was puzzled until she saw the phoine, which had gemstones instead of numbers on the keypad. Richie had to give her the dialing sequence in gemstones.
A mother of another girl in Totally Spies! bought a clothing chain just to get the last of a pair of exclusive shoes.
In the Futurama movie Bender's Big Score, Earth is taken over by alien scammers who buy a fleet of solid gold, Gem Encrusteddeath stars to defend it.
When Peter Griffin of Family Guy got a 150,000 welfare check every week, the first thing he did was rent the Statue of David.
In an episode of The Looney Tunes Show, Daffy Duck finally gets the wealth he so ardently desires and spends it on, among other things, a fancy-dress outfit (complete with powdered wig) and a hand-painted mural for the ceiling. He can't even go grocery shopping without embarking on a search for the most expensive brand of soup.
Parodied in South Park, when the boys are shown the evils of downloading music illegally by seeing what it does to the artists: namely, forcing them to do this to a slightly lesser extent(for example, having to fly in a private jet that's one model out of date, or not being able to give their kid a private island for his birthday).
Rarity, the fashionista in My Little Pony: Friendship Is Magic routinely uses large amounts of gemstones to decorate her outfits. On the other hand, gemstones seem to be much more common in Equestria (and are found pre-cut in nature) and Rarity can magically detect gems in the ground. When her sister uses up a whole crate of sapphires for a tacky (though heartwarming) picture, Rarity just goes out to dig up some more. It's fair to assume that ponies have no use for gems beyond decoration. Whereas dragons like Spike eat them like snacks.
Squilliam Fancyson owns a private yacht, a private lake, a private heliport, a private island and a Zeppelin casino.
Principal Scudworth devotes a considerable chunk of the advertising kickbacks he got toward having Mr. Butlertron gold-plated and lowered. The rest of the money disappears in a similar fashion.
Real Life
Live-in servants. The development of household appliances through the twentieth century reflects the increasing difficulties of finding decent hired help. The proliferation of the flush toilet in middle-class households, for instance, was due in large part to the burgeoning reluctance of increasingly better-paid servants to regularly empty and clean receptacles for other peoples' shit.
Macs aren't alone. For a while, Voodoo PC, which makes high-end gaming PCs, offered a model called the Omen AU. "Au", of course, is the chemical symbol for gold. Not only was the PC top-of-the-line for the time, the case was plated with 24k gold. Sale price: $15,000.
"I Am Rich", a short-lived iPhone app, costing $999.99, consisted simply of a glowing gem displayed on the screen. It was literally made for buyers to show off that they can blow a thousand dollars on nothing. The creator sold six before the app was pulled by Apple - mainly because some geniuses clicked on it to see whether it was real.
The Golden Opulence Sundae. A $1,000 sundae that's covered in 23k edible gold leaf, the sundae is drizzled with the world's most expensive chocolate, Amedei Porceleana, and covered with chunks of rare Chuao chocolate, which is from cocoa beans harvested by the Caribbean Sea on Venezuela's coast.
Serendipity-3, the creators of the Golden Opulence Sundae, outdid themselves by making what Guinness has declared the most expensive dessert in the world, the Frrozen Haute Chocolate tips the scales of Opulence at $25,000.
This is common with societies that combine extreme wealth with extreme inequality. The Victorian Era was notorious for this, as was the (very appropriately named) Gilded Age in America. It continues among the American super-rich, with Trump and his tasteless gold-plated everything being one of the most egregious examples. Oil wealth has enabled Mideast oil tycoons to take it to new heights: a tennis court atop a skyscraper, artificial islands in the shape of a world map, and canals in the shape of a one tycoon's name (HAMAD) are some examples.
Culturally most of East Asia is prone to this. Japan has traditionally had the most status-conscious, fanatical luxury shoppers. And China who for decades had a ridiculously low standard of living has been recently experiencing bouts of conspicuous consumption, where they buy items that shout out status (e.g. factory workers spending two months worth of salary on designer bags). In fact, when abroad the average Chinese tourist will spend more time/energy shopping than any other activity put together.
Studies show that conspicuous consumption is mostly practiced by the middle classes in an effort to look rich, especially when it comes to boats, houses, AT Vs, cars, and electronic devices.
The entire concept of World's Tallest Building is very much this trope. From the Eiffel Tower to Empire State Building to Burj Khalifa, this is essentially an enormous (pun intended) method of saying "screw you" to the rest of the planet.
Part of the Course for the Gaddafi family, as their fall made all clear. The patriarch himself was captured with a golden-plated Colt on his hands and also owned a golden AK-47 and a golden sniper rifle. But perhaps the most iconic was his daughter Aisha's couch, entirely made of gold and shaped like a mermaid with Aisha's face.
Nokia's Vertu line of cell phones feature such things as genuine gemstones and precious metal cases. Prices have ranged as high as $300 000 each for the most expensive models. For a period (before Nokia pulled out of the country entirely) these were the only Nokia-made phones available in Japan.