I don't think that's true.
Hamsik loves the city of Naples, he's no fancy guy. From what I read he also spends time and he sports in the much lesser wealthy areas in Naples. He likes to mingle with the people in the city and is exposed to them often. Lavezzi held relationships with members from the Camorra, no surprise he got mugged once or twice lol.
We could say the same about Turin being criminal with Bonucci's case and Vucinic's watch that was stolen when he first joined us. People are just too selective.
Naples isn't the wild west like some here are trying to make it seem.