The South Korean shooter was very troubled BUT
I think Virginia Tech clearly failed him.
He was a very troubled, anti-social South Korean kid. They put him in a dorm with All American type of rich white kids. I do not rule out laughs and abusive jokes about him on a daily basis. He left a note saying: "You caused me to do this".
He had absolutely no friends and was ignored by teachers and classmates.
Its really not so hard to understand that the kid eventually went nuts. College days can be long and painful when you are in that kind of situation.