Basically people who love horror movies are people with boring lives. They want to be stimulated, and they need to reassure themselves, because when a really scary movie is over, you're reassured to see that you're still alive and the world still exists as it did before. That's the real reason we have horror films--they act as shock absorbers--and if they disappeared altogether it would mean losing one of the few ways we have to ease the anxiety of the imagination. And I bet you'd see a big leap in the number of serial killers and mass murderers. After all, anyone stupid enough to get the idea of murdering people from a movie could get the same idea from watching the news, right?