Could also be that the school environment was simple hierarchy, and that Eric didn't fit in/wasn't strong enough to be at the top (survival of the fittest/natural selection type of mindset). He wanted to though.
He saw no problem with the way things were structured in the school, he personally wrote about removing all the "lower" beings from earth, people that were weaker. It wasn't the schools fault he didn't fit in, and had a bunch of friends, a hot girlfriend. It was his fault. Goes hand in hand with him hating himself a lot, and ultimately committing suicide.
Just a thought