What does this tell us? That those making $1 million or more are the “salaried rich,” since they make more of their money from ordinary income. The super-rich make more of their money from one-time capital gains from the sale of stock or a business.

Since the super-rich are so dependent on capital gains, their incomes have become much more volatile, falling 40 percent between 2007 and 2009. As a group, they also change members rapidly, with 73 percent of them showing up on the list only once between 1992 and 2009.

Income for this super-rich group “has become much more volatile during the Great Recession, “Williams writes. In contrast, income for the merely rich dropped 18 percent.

The higher they fly, the harder they fall.

-By CNBC's Robert FrankFollow Robert Frank on Twitter: @robtfrank

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