They pushed them out of Italy, which forced mafia to adapt in the US, eventually becoming richer and stronger. A much more powerful transnational mafia returned back to Italy.

That’s just the state mafia replacing the other.

One Mafia pushed the other out. No improvement for normal people.

Why does that anger you? Democracy is fundamentally unable to solve such issues.

With Putin's Russia transition to authoritarian and recently becoming fully totalitarian, the Russian Mafia of 90s (with the 90s being the most democratic time in Russian history), is pretty much no more. FSB and police have replaced them in the protection and extortion domain. Thus nowdays an arrested colonel of FSB or police may easily have a couple cubic meters of money (euro and dollars) at home, to the envy of many mafioso around the world. Or Chechnja - instead of many smaller (and poorer and less organized) warlords of 90s, now there is only one with personal army of 40000 and exploiting the whole region in the style of the most cruel mafia.

They can, they just don’t do it. This is the case in every western „liberal democracy“.