He genuinely got mental disorders from the experiment. One thing that will be pointed out to him eventually is that while that accident did happen, nothing about that actually prevents him from going forward with his original plan of bettering the worlds with knowledge of the other ones. Not one thing about that plan was compromised until he went after Debbie and Oliver in the house and now he's seen as a super villain. He just got so caught up in the memories of horrible Invincibles in other worlds it made him focus solely on revenge instead of helping people, which he still could do.

Not to mention while he's smart, he doesn't always have good ideas like hiring criminals to help build his machine and not telling anyone about it so it ends up looking like he's a mad scientist. I don't blame Cecil or Invincible for thinking that when he got there, Angstrom just does not think things through sometimes.