A 5 page article in the April 2002 issue of Harvard Business Review explains it all:

The basic inequality in wealth distribution seen in most societies may have little to do with differences in the backgrounds and talents of their citizens. Instead, the disparity appears to be something akin to a law of economic life that emerges naturally as an organizational feature of a network. Bouchaud and Mezard found that if investment returns grow sufficiently volatile, they can completely overwhelm the natural diffusion of wealth generated by transactions. In such a case, an economy can suddenly reach a tipping point, and wealth, instead of being held by a small minority, will condense into the pockets of a mere handful of super-rich robber barons.

If we are not yet at the End of History, are we at least approaching the End of Economics?