Of course, didn't Michael state that he received no proceeds from current illegal activities and that he had sold the casinos and divested himself of any interests in gambling, etc?
Yes, but it just seems that that is a recent development--I doubt he sold the Casinos or gave up other interests years before. My point is that likely up to at least the mid 1970s Michael still actively profited from illicit dealings. Even the current cash he had, the billions, the vast majority of it was probably gotten through illegal activities, so it's still blood money in any case.
Fun fact btw: I did some inflation calcuation. Michael's $2 million in 1958 (the amount he was going to invest in Cuba) is the same as about $15 million today. Even in the 50s he and the Corleone Family were very rich.
