I broadly agree with the post, but disagree with many of the claims.

In my opinion the root cause of unhappiness in school isn't bullying, inadequate exercise or other excuses (which apply to adults as well). It's that you're literally in prison  when, physiologically a 14yo should be out hunting deer and having kids. As Paul Graham put it

I'm suspicious of this theory that thirteen-year-old kids are intrinsically messed up. If it's physiological, it should be universal. Are Mongol nomads all nihilists at thirteen? I've read a lot of history, and I have not seen a single reference to this supposedly universal fact before the twentieth century. Teenage apprentices in the Renaissance seem to have been cheerful and eager. They got in fights and played tricks on one another of course (Michelangelo had his nose broken by a bully), but they weren't crazy.

As far as I can tell, the concept of the hormone-crazed teenager is coeval with suburbia. I don't think this is a coincidence. I think teenagers are driven crazy by the life they're made to lead. Teenage apprentices in the Renaissance were working dogs. Teenagers now are neurotic lapdogs. Their craziness is the craziness of the idle everywhere.

-  http://paulgraham.com/nerds.html

Also

I don't even remember seeing anything too terrible. Are people just blowing this out of proportion?

Adults only remember the fun interesting parts, they don't remember the 90% soulless crushing waste of time and minor torments because our brains have no reason to remember that.

I recommend this video, produced by a student after dropping out

Disclaimer: I'm high-school aged (17) and I've been unschooled and autodidacting my whole life, so while I can't speak from personal experience I can speak about the experiences of others my age whom I've talked to.

It turned out that at least around me, the most common answer was something like: “I always knew it was important and interesting, which is why I started to read about it.”

I found out about alignment/AGI from some videos of Rob Miles on Computerphile. It's possible you're around/talking to very smart people who were around when the field was founded (hence they came up with it themselves), but that's selection bias - most people aren't like that.