- Misreading the market: Probably the biggest real reason is that it's just plain hard to know what people will like. Worse, it changes all the time. What was innovative two years ago when you tried to Follow the Leader and greenlit the movie is now a tired old cliché nobody will see. Maybe you underestimated the audience… or overestimated them. The point is: sometimes even your best efforts fail.
- Bad word of mouth: Sometimes a movie does poorly because everybody's just expecting it to be a bad movie - maybe it's a sequel to a bad film, or it's in a genre that the Director isn't known for, or it's assumed to be a rip-off of an older movie, or a remake, or another Continuity Reboot, or the trailers were terrible... and often people just don't want to go to see a movie that they aren't sure they'll enjoy. This doesn't mean the movie is bad.
- Competition: This is particularly often in effect with summer blockbusters. People have a limited amount of brainless action they would watch, and if there's a lot of that available, some titles may be neglected. They also tend to be high-budget, and as such if the movie flops, it costs a lot. There is, however, often a principle similar to Award Snub in nature: several good movies (with similar target audiences) are released simultaneously, thus one of them performs truly spectacularly, another one flops, but both are considered great in hindsight (the hit E.T. the Extra-Terrestrial and the flop Blade Runner, for example).
- Poor Marketing: Many a bomb became so despite (or due to) being an excellent movie in general. Incorrect or misleading information about them (or just plain lack of marketing) makes audiences rely exclusively on word-of-mouth, which is generally not enough for a movie to successfully perform. The internet has made this situation a bit better, but not that much. These movies almost always achieve cult status and can later become profitable on DVD.
- Poor Budgeting: With the amount of money spent on big releases, this is an increasingly large risk. Even good movies can effectively fall down at the box-office if they cost too much to make. Tens of millions are spent on special effects that last a few minutes or sets that will inevitably be blown up, an actor's paycheck is extortionate, and if it all costs too much, you're going to reach a point where no matter how good a movie is, it just can't make back what was spent on it. The creators can only hope for good DVD sales and reviews and take home a little lesson for next time.
- It blows: Face it. For all the other reasons, sometimes a movie fails because it's just a terrible movie; the story, the editing, the acting, it all sucks. Somebody put a lot of money into it, and man, was that a bad idea! Cause it seems that absolutely everybody involved was doing cocaine or LSD at the time. The movie failed, sucks to be you, better luck next time...if there is a next time.
- Other circumstances: Sometimes movies flop due to something that's not directly related to the movie itself or the movie industry as a whole. For example, the first film to lose over a million dollars, Intolerance, came out at a time when its antiwar sentiments (which were widely held just months earlier) were going against the popular pro-war wave of late 1916. Funny Aneurysm Moments and Too Soon tend to hit disaster movies' sales very hard when bad timing happens; the September 11th attacks and the Indian Ocean tsunami, for example, killed a lot of those even though they were obviously filmed prior to the catastrophes. Maybe your headlining actor make a derogatory comment that leads to a boycott of the film. The same effect involves comedies lampooning airports, airlines, and the security process, which all brought down the film adaptation of Big Trouble, which was bumped to the Dump Months from its original position ten days after the 11th. Another example of unfortunate timing is if a movie's genre is killed prior to release.
Box Office Bomb
A Box Office Bomb (or less severely, a flop) is a movie for which production and marketing cost greatly exceeds its gross revenue, ergo fails to turn a profit for the studio behind the film. While in the press the two terms have some crossover, a flop may be applied to all disappointing results, but a bomb is outright failure costing studios millions. With today's budgets, you can even see losses in the hundred-million-dollar range. So, how can you tell when a movie has bombed? This depends on several factors. First is how much the studio paid to make the movie, paying all those people and companies you see in the credits at the end, which is generally public information. How much the studio paid to promote the movie is also an important factor. The marketing budget is generally not public information but is generally a significant percentage of the film's overall cost. A $150-million production may well have had $75 million spent to advertise it. Furthermore, since movie theaters don't just show movies for free, a portion of every ticket sold goes to supporting the theater itself. Put these together, and you can see that a movie mustn't merely cover its budget but probably needs to make twice that before it can begin paying for its marketing costs, much less become profitable. A common objection at this point is to bring up the international box office. After all, the film made several hundred million more than its budget around the world; clearly these studios just want us to think only America matters and the Hollywood press keeps buying it! Right? Well, actually… not really. Or at least, not always. While the rest of the world is a much bigger market and can rack up film returns in the billions, behind these numbers, overseas distribution is actually a lot less profitable for the studios themselves. Like with domestic theaters, foreign theaters need to make money off of ticket sales, and they're more inclined to support movies made locally as opposed to internationally-made movies. As such, films shown overseas will often see even less of a return than the domestic gross and may have additional costs like needing a local dub track. How much the international box office helps can also vary depending on the country in question. So studios still count on covering their costs domestically and judge a movie accordingly. While it's possible in practice, aversions tend to be from marginal cases. Around the world, taste in American movies tends to favor the same films, and the biggest hits at home are also the biggest hits around the world. Good further reading on how much movies need to make can be found here. Commonly cited possible reasons for box office failures: