Was Joker in it for the deal of half the mob money at first, and then after seeing how much fun it was, decided he didn't want the money and wanted to take over the city and be a better class of criminal? Or did he use the mob and the money all along to gain leverage enough to take over the city with his chaos? I wonder this, because he's also robbing banks at the beginning. He seems concerned with money and crime in the first half, then suddenly he's above money and is all about pure chaos.