Everyone has the right to make money. That's indisputable. What I have a problem with is the fact that person A can make millions of dollars annually for doing, proportionally, so much less work. Let's say person B works their ass off every damned day to make only $25k. Meanwhile, A is often doing very little actual work, be it back-breaking or intellectual.
I think this happens because of the importance, perceived or actual, of their work. Why does Gates make the ungodly amount that he does? I seriously doubt that he continues to write software for anything more than personal interest or satisfaction.