No doubt it is well known, no secret Michael is a Mafia Don, he was in the "legitimate" gambling business, owned or controlled hotels and casinos including the Hotel they bankrolled for Greene, the casino they took over, moving Klingman out

Only he had the key to his Fort Knox vault and unlocked it when he "sold the casinos."

They killed the New York Police Captain in a restaurant, the heads of all the other families, Roth at the airport surrounded by Police and reporters, got Pentangeli to kill himself in an Army barracks guarded by FBI and got away with them all No doubt brilliant

Michael's "legitimate" front was the Elephant in the room