Barney Kilgore, the man who made the Wall Street Journal into a national publication, was once asked why so many rich people favored higher taxes. That's easy, he replied. They already have their money.

That insight is worth recalling amid the latest political duet from President Obama and Warren Buffett demanding higher taxes on "millionaires and billionaires." Mr. Buffett is repeating his now familiar argument this week, coinciding with Mr. Obama's Midwestern road trip on the economy. Since the media are treating Mr. Buffett...