Bernie Madoff ran an elaborate Ponzi scheme for years. The SEC was repeatedly given tips and warnings over the years, but completely failed to discover the massive fraud. He was only stopped when his own SONS turned him in.
Anyone who starts a riot in a scene with a tense atmosphere. Seriously, who comes across one of those and thinks "Wow, this could use some violence!"
The thing about mobs is that they become collective idiots.
Villains can manipulate mobs that way.
A lot of customer service scenarios could be avoided or shortened if the caller did a simple, common sense action before calling. For example, if you're calling about a bill, have the bill readily available when you call, instead of just leaving it around somewhere and wasting a good 90 seconds looking for it.
Those seemingly patronizing questions at the start of some tech support interactions asking about whether certain simple, common sense actions were taken? They're in anticipation of this trope.
HBGary was a very important and security company, so much that the founder wrote the book on rootkits and it worked for the federal government and big corporations. Yet somehow, when Anonymous hacked one of their employees and then the whole company, it was evident that HBGary had made tons and tons of security mistakes that are dealt with in even a beginner's book. Unable to suspend your disbelief? Read this arstecnica article. The hindsights made in HBGary are so hard to believe that some people in the security world are speculating that maybe HBGary were acting as some kind of Honey Pot to trap anonymous later.
Denmark during the Napoleonic Wars. When Denmark seemed to become sympathetic to Napoleon, the British hijacked their fleet (an action that promptly led the Danish to support Napoleon anyway, so the ball holder could also be the British Empire). Some years later, Denmark was threatened first hand by Sweden, Russia and The British Empire for having supported the emperor, and the Danish king held on to France for bare life until he was attacked, promptly loosing most of his territories to Sweden. Denmark had to be forced to side with the winners.
Adolf Hitler grabbed the idiot ball during the later years of World War II and hung on for dear death. This wasn't seen as natural for him- many thought him a brilliant man with a great intellect, such as David Lloyd George, prime minister of England. But during the war he made many huge mistakes, most famously opening a three front war (Russia, Britain, America) with three immensely powerful countries simultaneously. His generals remarked that they thought Hitler's dog's mood had more to do with Hitler's military decisions than anything rational. He picked up the idiot ball hard.
In the NHL, if a team pulls the goalie in overtime, they lose the one point they would normally acquire after forcing OT. Los Angeles Kings coach (at the time) Andy Murray pulled Cristobal Huet to bring in the extra attacker in a late season game against the Columbus Blue Jackets. Andrew Cassels scored the empty netter, and the Kings lost that overtime loss point.
I'm not sure when this was, but since it was a late-season game, this wouldn't be nearly as dumb if the following circumstances applied: LA was on the playoff bubble; LA needed two points, rather than just one; and the team was poorer at shootouts than Columbus. Going with the extra attacker would hopefully prevent the shootout, and get the two points. A gamble (with not an unreasonable chance of success, especially if the team does well on the power play) that was lost, rather than a total Idiot Ball.
Gerald Ratner of the Ratner Group built a wildly successful chain of jewelry stores that grew during the 1980s by selling low cost, passable jewelry to the British masses. An accomplished businessman, right? Well, in 1991, Ratner picked up the Idiot Ball at an Institute of Directors speech. While giving the speech, he told the group, which included press, that he was able to market his jewelry at such a low price because "it was total crap". He went on to add that a pair of their earrings could be bought cheaper than a prawn sandwich, and probably wouldn't last as long. The story went public and suddenly, Ratner's once popular jewelry was seen as, well... total crap. The value of the company dropped £500 million, Ratner was fired from the company and the whole group had to change its name and retool its image to survive. To this day, the phrase "Doing a Ratner" is slang in the UK for improbably stupid business gaffes.
Imperial Japan's attack on Pearl Harbor set in motion a massive military campaign against them that resulted in a bloody conflict over the course of almost four years. The US rapidly destroyed their navy and flattened their industrial centers in a series of bombing runs that would culminate into the most powerful weapons in human history being used to force them into surrender terms. Meanwhile the Soviets took the opportunity to liberate Manchuria from Japanese occupation.
This is a particularly Egregious example since there was absolutely no advantage to the attack, and countless drawbacks that even a 10-year old could foresee.
Had they actually managed to cripple the US Pacific Fleet, there would have been a (temporary) advantage to the attack. As it was ... they sunk the Arizona and a couple of other ships of lesser importance, and they managed to damage a few more, several of which were back in service within months. They notoriously missed the carriers (which weren't even in the harbor at the time) completely. There's a case for YMMV on whether or not it was a known high-risk, high-reward gamblenote Think to Yamamoto's quote about six months of running wild...... but it'd be the Idiot Ball if the Japanese military hierarchy didn't recognize it for that.
Four days after the US declared war on Japan, Nazi Germany declared war on the US. While it was based on Axis allegiance, the declaration on Germany's part was the epitome of idiotic, as Nazi Germany was stalemated on two fronts. America merrily hopped onto the allied band wagon, high fived its best friends France and Britain, politely shook hands with the USSR, and proceeded to have a curbstomping party at Hitler's expense.
The French though couldn't high-five back, being indisposed as they spent most of the war being under German control. La Résistance, however, loved having a few new friends to help them with being professional pains in the ass.
Imperial Germany's decision in 1917 to offer alliances to Mexico (who was in deep civil war) and Japan (who was at war with Germany) against the USA (whose government was sympathetic to the Entente but not at war with Germany) thinking that this was the best way to prevent the US from joining the Entente was not very sound. But the really idiot ball came when the German Foreign Secretary Arthur Zimmerman sent a telegram to the Mexican government offering a completely unrealistic offer to help them reconquer Texas, Arizona and New Mexico (which Mexico didn't want anyway) through the only transatlantic cable of the time, that was operated by their British enemies. The British happily shared the info with the Americans and when they asked the Germans, Zimmerman came front and confirmed that it was a real proposal rather than a British plot to get America to declare war on Germany. The US populace, who had been deeply divided over the war and mostly favored non-intervention until that point, massively jumped in favor of war with Germany, and American forces arrived in Europe right in a critical time when Germany could have won otherwise, having knocked Russia out of the war.
During his reign as emperor of Rome (37-41 AD), Emperor Caligula decided to declare war on Poseidon. He had Rome's hundreds of thousands strong army march to the sea & start stabbing the water, then he had them bring back seashells, which he proceeded to eat.
Well, he's the Trope Namer for The Caligula, which is all about psychotic rulers. Stupid? Most likely. Completely and utterly insane? Yes!
In the English Premier League back in 1996, Southampton F.C manager Graeme Souness received a call from someone claiming to be world footballer of the year, George Weah. He claimed that a 'cousin' of his; Ali Dia, had played for Paris Saint-Germain and was a full Senegalese international. Now you'd think as an experienced manager and former player, Souness would have attempted to verify this was in fact Weah, or check Dia's supposed credentials, right? Nope, he in fact invited Dia down for a trial at the club. Matt Le Tissier remarked how he wasn't verygood. So you'd think after seeing his performance, that Souness would have released him and moved on, right? Nope, he was in fact named as a substitute against Leeds United, ironically coming on in place of the injured Le Tissier early on, only to be so bad that he was subbed himself later on! Once people started catching on that this might have been a wind up, Dia feigned injury and left! Souness himself would be sacked at the end of the season due to poor performances. Dia is now regarded as perhaps one of footballs worst signings.