Or should I lose hope in humanity completely now?
Yes they do.
It really just depends on the person, and how introspective they are throughout their lifetime. Some people get worse, some people get better. Events can happen that shapes a person’s trajectory in one way or another.
Less of a twat, but more cranky.
From what I’ve seen it’s a bell curve most of the time. People grow up and stop being little twats and eventually get to the point where they start to become big twats.
Yes until 70ish then some go full on shit head.