I agree with you that it is in our nature as beings with one perspective to be selfish, however it is also in our nature as beings with intelligence and empathy to be logical. Capitalism and class enhances selfishness and is a product of our selfishness, however the breakdown of our society into proletariat, bourgeoisie, and animal (the third class), means we are closer than ever to completely eliminating class, we just haven't used a successful method of proletariat control of the means of production yet.

Unquestionable idea come from two sources: group-think and class. The ruling class largely determines the ideas perpetuated through group-think, this is how democracy is flawed (however dictatorhip is even worse). In all hitherto societies, one of the drives of the ruling class is to perpetuate selfishness over logic, to idololize wealth without considering it's origin. If we look at primitive anarchist societies, we see that everyone cared deeply about the equal distribution of wealth and joy, as opposed to our current capitalist system which fetishizes this concept of deservation, whereas deservation and intelligence is manufactured by the rich and even if it wasn't, we should distribute wealth based on need, not deed.