Yeah, I can put Lefty down for masculinity and as Pizzaboy said "what a man should be." When they are all in Florida, there is a scene where the rest of the crew asks Lefty when he is going to bring Annette down to Florida and he says "when you bring your wives." This is him being a gentlemen and not bringing Annette down to the level of a goomah. Except, Lefty has a lust for power and I suppose by extension greed. Lefty has been kept away from the volcano so to speak and also has a gambling problem, which keeps his money low. He thinks he can be something more, but most just see him as a button who has 27 hits under his belt or however many it was. Maybe if he wasn't a gambler he could've got upped to caporegime.

Michael seeks power, and I am sure he is greedy as well although that is less explored. Think about Godfather III, he still needs to be in that position of power even though he states that he wants out of the life. He brings himself back as much as they pull him back in.