Former Secretary of State and presumptive 2016 Democratic presidential candidate Hillary Clinton was challenged in an interview published over the weekend by the British Guardian newspaper to establish her credibility -- as a multi-millionaire -- on the issue of income inequality. Clinton responded that those concerned with the topic “don't see me as part of the problem ... because we pay ordinary income tax, unlike a lot of people who are truly well off, not to name names; and we've done it through dint of hard work.”

Clinton's repeated clumsy comments about the wealth she and the former president have accumulated since leaving the White House in 2000 raises doubts about her political skills should she run for president. This particular comment evinces deep ignorance of who holds America's wealth. Clinton was trying to make an exception for herself by arguing she works hard and pays a high tax rate, but the overwhelming majority of wealthy Americans already meet that standard.

Multiple recent surveys suggest that more than 80 percent of U.S. millionaires did not grow up wealthy.

For 2011 (the most recent year of available data), the IRS reports that the share of all federal income taxes paid by the top percentile of earners (35 percent) was nearly twice as high as their share of all U.S. income (19 percent). They also paid income taxes at an average effective rate (23.5 percent) substantially higher than the average middle-income earner (7 percent). Hillary Clinton may have paid an even higher rate due to the nature of her massive and rapidly accumulated income (from her and her husband's speeches and books over a very short period), but she is not alone or special in having paid her share.

What about “hard work?” Clinton, who gives speeches at $200,000 a pop and reportedly received $14 million advances for unmemorable books, may not want to go there. The 9.6 million American families with $1 million or more in wealth today are overwhelmingly self-made, put in grueling hours to get ahead and had a unique combination of grit and brains. Few are former first ladies who can cash in on their names.

Multiple recent surveys suggest that more than 80 percent of U.S. millionaires did not grow up wealthy. This has long been the case in America. Days before Bill Clinton's re-election in 1996, Thomas Stanley and William Danko published The Millionaire Next Door, which found that they tended to live modest lifestyles and worked between 45 and 55 hours per week. Eighty percent of millionaires in their research were first-generation wealthy, with more than half inheriting nothing at all. Stanley and Danko also also cited the late economist Stanley Lebergott, who studied 4,047 American millionaires from 1892 and found that 84 percent “were nouveau riche," having reached the top without the benefit of inherited wealth.

America does not aspire to be a land of equal outcomes. Yet this nation has traditionally been exceptional in the world for the comparative equality of opportunity it affords to those who aspire to earn money and build wealth by working hard and investing deeply in sweat equity. These conditions have made America prosperous. It is perplexing that Hillary Clinton does not appreciate this, and unflattering that she looks down upon the sacrifices and hard work of her peers.