So what happened? Why did this young man do this?
What went wrong with is thinking that he saw this as a good idea?
From the articles about him in High school, he felt above others. He looked down on athletes and band kids. BUT he was not succeeding like he felt he should have been. He couldn't be to blame so he blamed and hated others.
It actually sounds a lot like Eric Harris (Columbine) and that guy that went around shooting girls at the college because they weren't interested in him. (I forget his name).
Edited to add - Elliot Rodger, 22, is the name.