I think they became less stupid as the mob grew into the 60s and 70s. The original immigrant gangsters were more compliant with the leaders mostly because they didnt know anything else, they were more content with whatever the boss was giving to them, or whatever money they were making. The men that came after them were not like this , to them they wanted more of a boss lifestyle, meaning that they were alot more ambitious than there forefathers and knew more about the opportunities that were out there. Drugs was just a small part of this change, inevitably this would have happened anyway.