Show business, being primarily driven by the profit motive, tends to focus on ideas to which an audience can relate and enjoy. The story of the RMS Titanic, being one of the worst peacetime maritime disasters in history, is generally antagonistic toward these ends because most (not all) people don't like thinking about the possibility of dying on an ocean-liner and do not enjoy watching it happen to others.

It should be clear how these two are in opposition. For this reason alone, conventional thinking would call a movie about the Titanic a "bad idea."

The movie worked, though, and made a billion dollars because the director executed it in such a way that it actually wasn't about a sinking ship and people drowning, it was about something else. And this other thing (call it the human spirit or what-have-you), overcomes the tragedy of the situation to make it something the movie-going audience could relate to and enjoy.

From a more technical perspective, the Titanic story could be considered a "bad idea" because, on the surface, the plot should hold no surprises to anyone: boat sets sail, boat hits iceberg, boat sinks, passengers are drowned.

The remarkable thing about the Titanic film is that EVERYONE knows how it's going to end, even before they sit down to watch it. This, according to conventional wisdom, would be a bad idea as far as show business is concerned. Who wants to see a movie like that? Yet audiences returned to theaters multiple times. It is a credit to Cameron's direction that the film could overcome such a large, inherent obstacle in the Titanic storyline.