My daughter and I like to watch series about true crimes, mysteries and such. What we see on these shows is far more frightening than any horror movie. These are real people. Monsters do exist. They masquerade as humans.
I wrote a post once about the fascination with serial killers. One series we are watching tonight actually speaks about the why. Which, in my opinion is the reason for the fascination. The psychologists in this series say that psychopaths are born that way. BUT that not all psychopaths turn into serial killers. Environment is a major factor. If someone is born with a chemical imbalance or psychopathy and suffer neglect and/or abuse then things can get very ugly.
I don’t know for sure. I have my theories. One thing I do know. Real life is far scarier than any horror movie.