Is it hard for a bully to sincerely change?

Usually bullies only apologize after a parent makes them do it or they are threatened at the principal's office with a suspension. Then if they do apologize on their own, it's after so many years later passed and you've already long moved on. It's then usually done as a result of a BS 12 step program. So basically you'll be waiting for a lifetime for a single apology. You needed closure at that time, not 10-20+ years later.

Very rarely have I heard of one that's actually remorseful after a short time (days to a couple months, without any adult intervention) and apologizes on a timely manner, not many years later.

Is it really hard for them to sincerely change and actually notice how wrong it was what they did?

Updates
18 d
It takes a special type of personality to enjoy harassing someone at that moment, to get pleasure out of making someone miserable.
Is it hard for a bully to sincerely change?
Post Opinion