In the continuing debate over the distribution of wealth and income -- the richest 1 percent of American families control more wealth than the bottom 90 percent -- one school of thought says findings like this, however extreme, do not present a true picture.
In this view these data are flawed because they are snapshots of a moment and fail to reflect the constant ebb and flow of fortunes.
Even if the raw numbers are accurate, these economists say, the portrait fails to capture the amazing fluidity of American society.
And the richest person in America these days is not a Rockefeller or a Du Pont but William Gates, founder of Microsoft Corp., the leading software company.
But modern Horatio Algers notwithstanding, a wave of recent studies shows that rags to riches remains the economic exception.
Though many doors and many rewards are open to talent, being rich or poor most often carries over from generation to generation, and certainly from year to year.
If anything, economists say, the climb out of poverty has gotten harder in the past decade or two. The U.S. economy has become increasingly less hospitable to the young, the unskilled and the less educated.
It is highly unlikely that this year's rich man will be next year's pauper -- or vice versa.