In the last few decades, the concentration of income in the United States, Britain and Canada has reached levels not seen since the late 1920s. Such extreme income concentration created a dynamic that led to the disastrous Wall Street crash in 2008 - just as it did in 1929.

The financial collapse is simply the most striking example of the problems caused by the rise of a new class of billionaires. Their massive fortunes - widely considered benign or even beneficial to society -- are actually detrimental to everyone else.