He was in an altered state for a very long time. People ostracized him, shunned him and rejected him. Nobody offered him the kind of respect, dignity, compassion and healing he really needed and could not provide for himself. The society's adamant refusal to look at behavioral health challenges helped push him over the edge. He knew people feared and hated him and got deeper and deeper into his resentments and frustrations over that. I know this from personal experience.
This society is very sick and toxic. Some people can't function in it because they are too sensitive or too damaged. The society tries to pretend it works and, when it sees someone who's falling apart in it, goes into total denial. The hostility heaped on people like me comes from the fact that, in their heart of hearts, people know damn well it could happen to them, too. That's why they pretend we have weak characters or are just lazy or self indulgent: trying to blame us for the shortcomings of the society.
And there's such a stigma attached to asking for help, for needing help. And the only "help" out there is incarceration or drugs, which are chemical restraints, not "cures" or even management of conditions. And the drugs are toxic and reduce lifespan by twenty-five years over a non-medicated person.
So, he was backed into a corner.
I'll tell you something else: I understand, even though he wasn't very articulate about it and people say he was just "rambling," which is another stereotype, what he was trying to say about grammar.
There's a jargon, a set of code words, different classes of people use in this country. The academic elite is an example: if you're not one of them, you don't understand the subtext of what they're communicating.
He was fed up, unwanted, frustrated, abuse and shunned. And he took revenge, hurting others the way he'd been hurt.
No, people like us are not, intrinsically, "dry tinder." It takes many years of shunning, abuse and neglect to create someone so resentful. There is a point at which a person doesn't care anymore about anybody else, because nobody cares about us. There are 3 ways of dealing with that: become society's helpless victim, become a recluse (my personal choice) or take out as many as you can on a suicide rampage, which is what is was, but nobody killed him. He left suicide messages.