I'm not sure you caught the point of the quote, which was not to explain the Columbine shootings. This teen was expressing why *he* was turning to some antisocial activity himself, due to a couple of factors: his search for something that felt "real" combined with pressure from parents and school to perform in school (where he has always struggled). He would like to leave school but his parents do not understand, as they equate schooling with "success" in life. I think that his own perspective on Columbine is affected by his own struggles to deal with stress at the moment.

At the same time, there probably is some partial truth to what he says about Columbine, and I don't disagree with him that stress in teen lives is not a major problem. Another mom who just took her anxiety ridden 16 yo out of school locally said there have been 3 suicides at her daughter's small rural high school this year. Oh, and the school tried to tell her she could not homeschool because she was a working parent.
Leslie in KY

So what is the cause of this generic "stress"?

I don't think it's appropriate to give any simplistic answer to "what is the cause of this generic stress?"

I do see a combination of complex issues at work here. For many kids, school is a big source of stress. Kids are told success in school is the only route to having a happy life and they can't see past the lie. Being put with same-age peers in large numbers creates a lot of social issues that cause stress. Loss of close family bonds is a source of stress. Being raised to be materialistic and looking to constant entertainment for "happiness" is a cause of stress. Having meaningless, purposeless lives by being confined to meaningless busy work in school, as Gatto talks about, is a big source of stress. My 21 yo tells me lots of her age peers also think the society we have created is headed for catastrophe, we just can't sustain this monster we have created. That is a source of stress.

I work with a number of square peg kids after school in private language therapy and several are on anxiety meds, OCD meds, etc. One boy who has a lot of language challenges obsessively computes his grade point average with a calculator in his free time at home. He said he's working on stopping doing this.

Lots more ideas here, but lots of kids are under a lot of stress from what I can see. Not that life was meant to be stress-free, but when you start getting suicides and dysfunction in large numbers it should set off some red flags.
Leslie in KY

I just found the word "stress" to be simplistic, that's all. Sorry.