I think we are all mentally ill, those outside the asylums can just hide it better. We all know people who talk to themselves, pick thier noses, make weird faces when they know they aren't being watch and who have hysterical fears. Why we pay $7 to watch a sadistic gory movie. Why do we enjoy watching others menaced and sometimes killed? Stephen King once suggested that if pro football has become the voyeur's version of combat, then horror films have become the modern version of public lynching.