Why are most bullies sorry only if their victim becomes more successful than them?

Not all victims of bullying become highly successful but when it happens, suddenly most former bullies are sorry. Why?

This is what happens if the victim moves on in life, has kids but doesn't become as successful nor wealthy as the bully:

The former bully (however he resigned by now... his reputation suffered ever since) is heard laughing even after 35 years later; he still finds it funny.

Why are most bullies sorry only if their victim becomes more successful than them?
Post Opinion