It's a betting game, upheld by the assumption that as bad as it is, it is the best method we've got to determine the 'value' of a thing (you reach some interesting philosophical questions very quickly this way).

John C. Bogle has written angrily at length about this many times in the past. I don't know enough to say whether I agree with him or not, but "The Battle for the Soul of Capitalism" was a fun read. He basically pushes forward his thesis that many problems related to corporations and corruption have to do with a transition from "shareholder capitalism" to "manager capitalism".

I read it so long ago that I'm distorting things, but I will always remember that it was way better than the stupid title made it seem.