A lot of the bad in the world comes from leaving people unequipped of certain basic "soft skills". It's not the same thing as mental illness, but it has similar effects.
And, for some reason, people become seemingly completely unwilling to learn-by-example any new-to-them soft skills, once they reach adulthood.
Or perhaps "lifelong learning of soft skills" is itself a soft skill that people aren't being taught.
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Anecdote: I was diagnosed/treated for ADHD as an adult, whereupon the "social soft skills" part of my brain suddenly started working like it never did through my childhood.
I went from thinking I was on the autistic spectrum, to noticing all sorts of new patterns while observing social interactions. I quickly realized that my capacity for social-skill learning had never been missing; but rather, the learning itself had just sort of been "paused", for lack of "voltage" in the right brain areas.
I did / am still doing a lot of delayed soft-skill learning as an adult. And it's really starkly obvious how much other people with me in the same situations, aren't deriving the same learning I do from those situations — even when those people are sorely lacking in the relevant social skill, but aren't otherwise socially unskilled. It seems like they just aren't bothering to look at the situation under the right "lens" to see the pattern, even though it's a "lens" they clearly possess.