But millions of people are and have been bullied, and these school shootings are still rare enough to be exceptional, not the norm. It's not bullying that's the direct cause; perhaps a contributing factor, but that's all. The real problem is a combination of things. It seems to me this guy was beyond narcissistic. How else do you explain him sending that video to NBC? And the contents of it, from what I've heard, seem to be him railing at 'rich kids' and trust fund babies. In other words, he was self-absorbed and jealous, not to mention likely clinically depressed and on some medication.
The level to which this was planned also showed that he didn't just 'explode' and kill a bunch of people. He was methodical, and knew exactly what he was doing.
As for the guy being arrested, I can't say I'm terribly sympathetic to him personally, and I'd say he needs a good beating, but I really don't like the idea of arresting a guy for words. Unless he actually called for someone's murder, of course.