Furio, I don't think there are sources other than claims made in books. But of course these books come from different eras. I'd say they still make more than enough money otherwise they wouldn't be in it. Crime only flourishes because there's money to be made. And if some kid pushing pills or weed on the streets can earn 2000-4000 in some weeks, a boss can earn millions. But we have to take into account they arent able to spend it all freely off the bat, they'll be worth a lot, but not have a lot of legal spending "power".