Simple supply and demand free market economics. You can get paid that much too if you can find find someone willing to pay you for your services. We have gotten ourselves to a strange place in our society where we make villians out of successful people, regardless of the industry they are in.
That being said, I do think it is incredible that they get that much, but more power to them. I'm not a fan of the Hollywood elite's politics, but I do support them in their ability to make as much as someone is willing to pay them.