Um, he DID go to a mental hospital. People like that are so deep into their own bullshit, they're almost bound to it. I doubt anything could have helped him.
This is one of those situations where a spectator can't make a judgement. You weren't there, you may have comprehended something differently int hat situation/environment. Once again, I think people make these authoritative calls only because they've seen the outcome, so they think it's clear to them how it could have been prevented.