It's the media's fault. If they didn't revere every loser who shot a couple dozen people as a god, these guys would just kill themselves and be done with it. But when you can go out with glory... to be the most important person in the world for a whole week... it'd almost be hard not to.
I hear this all the time, and I don't think it's that simple. Some people are suicidal and angry at the world for their suffering.
Media coverage is probably a minor influence in them wanting to exact revenge.
People often joke, "if I'm going out, I'm taking a whole lot of motherf*ckers with me". Nas has rapped, "Could use a gun, but **** bein the wanted man.. but if I hit rock bottom, I'ma be the Son of Sam".
Of course these are just jokes and fantastical lyrics, but it does hint at some impulse that lies within some people.
Good on the Canadian Youtube people for taking the threat seriously. I imagine myself reading some internet comments on ISH or whatever of someone talking about shooting up a school and I can't say I would have done anything. We all need to take note of this and be more conscious of the warning signs. It seems like a lot of these killers act out before they actually commit the crime. They are looking for help and we need to be aware enough to recognize that fact.