Whatever else they are, the super-rich have now become political props. We can thank President Obama and Mitt Romney for this. Obama thinks he can ride resentment against the rich into the White House for a second term; and Republican Romney's fortune, estimated at $190 million or more, qualifies him as super-rich. By all means, Congress should pass the "Buffett Tax," named after billionaire Warren Buffett, who noted that his 2010 tax rate (17.4 percent) was about half his secretary's. The explanation is that Buffett's income comes mostly from dividends and capital gains - profits on sales of stocks and...