Rich Lowry: Middle-class Joe cashes in

The American middle class just got a lot richer.Joe Biden, who invariably and tiresomely refers to himself as "Middle-Class Joe," made $15 million the first two years after the end of the Obama administration.This hardly qualifies as a rounding error in the portfolio of any billionaire mogul, but for the average American, a million here, a million there, and pretty soon you're talking about real money.According to one estimate, it takes an annual income of $420,000 to be in the top 1 percent of