There was huge money to be made in the USA for decades starting with prohibition, while Sicilian mafia and 'ndrangheta were just a bunch shepherds and farmers in an underdeveloped country.
yes, american mafia was richer and more powerful than italian mafia in the 1940/50/60, and it was probably the strongest criminal group worldwide at that time italian mafia became stronger and richer only after the 1960s, and it was at the ending of 1800/beginning of 1900
