Why did Eric and Dylan commit NBK?

Why did they do it?

Because they could and felt like doing it.

That's the main line of reasoning I have concerning NBK right now: two boys had the crazy idea to go kill everyone they felt didn't deserve to live, spent more than a year planning something that'd ultimately end up being quite a bit of a failure, and nobody in all that time had the coherency of mind to put a stop to it despite very strong hints from both that something was wrong. I think they felt like the world around them 'had it coming because they didn't see it coming'. I think it was the ultimate 'fuck you' to a society that neither felt they belonged to. (Whether they actually did belong, or could've belonged, is beside the point: the boys didn't feel they did, so they took up the position of omega in the pack regardless.) Why did they do it? I think the main question they would've replied with is "why not?".

Good post Dragon.

I've always thought the boys made it perfectly clear why they did NBK: they wanted fame and revenge, they wanted to make a statement about social mendacity and ignorance, and they wanted to take pleasure in the murder and destruction of the people and places they despised. Also, I think neither of them had any self-identity outside of the Reb and Vodka personas they'd created to get through adolescence and survive as long as they did. High school was about to end and that also spelled the logical end of Reb and Vodka. In the end, what was left "under" the Reb and Vodka personas was just two terrified, shunned children whose self-esteem was so low that only thoughts of homicide and suicide offered them any respite whatsoever from misery and self-loathing.