I heard it said on the news that during 'critical times hard to deal with' that people enjoy watching something scarier than they are experiencing in regular life so that the things they see on the news don't worry them as much.
They are then able to say, well, it could be WORSE!
Being able to get scared and leave it enables them to be stronger with reality thinking everything will be okay.
I personally stay away from them. I don't need any more horror in MY life. I look for comedy or nature.