[T]he interesting policy questions continue to be, first, what are the sources of the wealth and, second, what distortions result from it. On the first, it seems to me that we should obviously think differently about money earned from superstar effects and money derived from access and rent-seeking. Rich [growing] wealthy from the invention of Google or bets against an unsustainable housing bubble are in a different category from those who happened to know the people doling out government contracts or mineral rights.
But the second issue is actually the more important, and it's the one for which we currently lack a firm grasp. What does this concentration of wealth mean?