Box office numbers are purely marketing -- people follow what other people do. Just like CBS has been advertising "We're the #1 comedy channel, football channel, etc.". So it really helps to have big box office numbers.
Once you understand this, it helps you interpret the bald-faced lies that Hollywood makes when commenting on box office numbers.
From BoxOfficeMojo: "I think the industry and the media did not understand how a three hour movie performs," said Marc Shmuger, vice chairman of Universal. "Take Lord of the Rings out because that comes with the Tolkien nuts, and there aren't any examples. It's not surprising that we didn't understand it. As crazy as it is, the only one you can point to is Titanic. [King Kong] is writing its own pattern."
No, actually Shmuger, the highest grossing movie of all time (in adjusted dollars) was FOUR hours long. It was called 'Gone with the Wind,' maybe you've heard of it?
Epics sell slowly. We know this. That's why Titanic did the numbers it did, it was an epic (sad, but true). Star wars (the first three) - Epic. Raiders of the Lost Ark - Epic. Obviously, from all of the hype, Universal is desperate for King Kong to be an epic. But you have to wonder if it is ultimately in the same category as Every Which Way But Loose or Bedtime for Bonzo.