I always loved what was posted on Cracked a long time ago, and makes total sense:
In Harry Potter and the Goblet of Fire
If Harry decided to do nothing, nothing, after his name was picked from the Goblet of Fire, there's really no way anyone could have forced him to compete. Even if the judges insisted upon obeying a magic cup and entering Harry into every event, he could have stayed home and watched the whole thing on Pay-Per-View, scoring a solid zero points at each tally. Seriously, what was the cup going to do to him if he didn't participate? Kill him? Apparently not, since he shows up late for one event and the cup wasn't coming after him with a dagger or anything.
Hell, Hogwarts wouldn't even have had to lose their chance at the title, since they would still have had Edward Cullen competing in the game. Who, incidentally, would also not have been killed if Harry had backed out of the tournament.
We can also probably assume that any reprimand that Harry might have received for brazenly defying the orders of magical kitchenware would likely have been revoked after it was revealed that his competing would have led inevitably to the release of a powerful supervillain, and to Snape killing Dumbled