There's no shortage of scapegoats in the credit boom and bust: exotic derivatives, overpaid executives, baby boomers. Yes, the generation that brought us hippies, then yuppies, then old people on Facebook is a culprit in the economic crisis. As the 79 million boomers have aged, the U.S. economy has reflected their habits. It's no coincidence that the dotcom bubble and the early-2000s credit boom happened when boomers reached middle age-consumer spending peaks around age 46. Now, as boomers close their wallets and prepare to retire (the oldest of them became eligible for Social Security in 2008), they'll start dragging down the economy instead of propping it up. "Baby boomers have peaked," says investment manager Harry Dent, who has long warned of this coming demographic crisis. "They're going to slow the economy down for the next 12 to 14 years." This is exactly what happened in Japan, where an enormous asset boom crashed in 1990 just after a big chunk of the population hit middle age. Japan's economy never recovered, and the Nikkei is still about 75 percent below its 1989 high. Could the same thing happen in the U.S.? One piece of evidence suggests yes: the U.S. today has a median age of 37, roughly the same as in Japan 20 years ago. Only one consequence seems certain, however: we're in for another round of boomer navel gazing.