Why do they have horror moves?

Answer 1

The simple, pragmatic answer is: because people will pay money to see them.

But why is that?

People enjoy scary make-believe. Horror movies always turn out ok in the end, with some sort of justice, vengeance, or rescue.

First you magnify the fear, and then you relieve it. It's very reassuring to feel that no matter how horrible it gets, everything will be all right in the end. In real life this is not so, but in movies it is comforting. It is also cathartic:

the purging of the emotions or relieving of emotional tensions, esp. through certain kinds of art, as tragedy or music. [from Dictionary.com]

Horror movies don't do it for everybody--some are too scared or grossed out by the horror part (although a really good horror story does not need to show a single drop of blood; horror and slasher are not the same thing at all). But some people really feel like they've been through something and survived. Whew! Great. ----