Going to a college or university and graduating with a degree are two different things.

When I was attending an excellent university the majority of people I met my freshman year did not graduate at all.

Most dropped out, or failed out. Many would just stop going to classes that they'd taken loans out for or had their relatives pay for.

I doubt the majority of mafia guys you wrote about actually graduated. The guy in Italy who was an M.D. but then joined the mob is an idiot and probably went to a joke of a med school in Italy or just paid a lot of money for his degree.