Do celebrities want to save the world?

Everyday, it seems, I'm bombarded with news from celebrities and their trips to some impoverished African nation to raise awareness and such. I can't help but feel cynical that these people want me, who makes 20,000 a year, to donate money to these charities when they donate a million, which is only a small chunk of their earnings. Anyone else feel it's bull when Angelina Jolie preaches about helping people and then buys a 6 million dollar yatch, and schedules a 2 million dollar photo shoot of her new son 2 days after adopting him? With so much money they can make an even bigger difference but it seems like Jolie, Madonna and Bono really don't want to enough. You can live well on a million a year and yet they keep tens of millions.