As explained in Reason.com:
Piketty is being celebrated for supposedly demonstrating that the deep structures of capitalism tend toward ever-greater inequality. But in the United States—the most unequal of all the advanced economies—the main explanation offered for the growing gap between rich and poor is that 100,000 or so corporate managers are being overpaid. What’s getting all the attention is Piketty’s depiction of rising inequality as the tragic flaw at the heart of the entire capitalist economic system. But what’s really going on, at least according to Piketty, is a comparatively narrow and shallow problem of corporate governance.