Sounds like the author has personal problems they're mistakenly ascribing to their work. Many of their assertions are simply not true (It's possible to be confident without "being an asshole"; I know several such people), and it just comes across as written by an unreliable narrator (if I cared about this person's issues, I'd likely be asking the people who shunned him about what happened and see if the stories match…
That said, it does look like the author possesses some level of self-awareness and is working on his issues.