Why are there so many psychos and serial killers in the USA?

What is it about America which makes it so full of psychos. I mean it has the highest number of serial killers, highest number of mass shootings and school shootings, very high rate of rape and gang violence. In 2008, 1 in every 100 people were incarcerated in prison. That is a shocking fact but it is true. If you look at the list of serial killers on Wikipedia the USA takes up most of the page!! Why is it like this? What is it about living in USA that drives people so insane?