I also know a number of people in the scene who lost their sanity through drug abuse. It is sad, but when you are partying and abusing yourself every weekend for years on end something is going to give.
I'm not saying there isn't a correlation with partiers who do lots of drugs and mental illness, but I have watched a lot of people lose their minds across all my social circles.
It seems like a certain percentage of people lose their minds in their early 20s.