Common guys, it not always about money, if you look at the richest people in the world - Gates, Simms, Branson - they all started out looking to make billions, when they finally did make billions, their focus turned to making a name for themseleves.
At some point in a players career, they will have earnt more than they can spend and will want to be the best player in the game, both for club and country. Pato, playing for Milan, has that opportunity and will want to be remembered for being a one of the GREAT brazilians of the modern game.
I honestly believe that pato will start to perform when he gets back from injury, he has nothing else to do but prove himself. Their is also the world cup approaching in Brazil, which will be an added incentive to kick some arse.