Unequality, economy and reward

Unequalities of income have reached an unprecedented level in the US, and, although this distortion is generally not questioned, a few critical voices are beginning to rise.

This video is an equilibrated discussion of the topic. It states that high unequalities are related to poor economical performance. In a nutshell, this is the second book of "The Capital", but I don't want to discuss the economical facet of the question. I would better address the ethical aspect of unequality. Supporters, claim that unequalities are healthy, since they prvide a reward for the skilled and the enterprising. This is maybe true, but provided that unequalities do not presresent an impassable barrier. When the unequalities are exaggerated, they become impassable, and we are no longer in an open society, but in a society of castes.