The U.S. is headed for “the most predictable economic crisis in history,” as Bill Clinton’s former White House chief of staff once put it. Why? Because of the mountain of federal debt that we keep making bigger and bigger. For the first time since the wartime economy of the late 1940s, U.S. debt is roughly equal to the value of all the goods and services our economy produces in a year. When World War II ended, all that spending on tanks and aircraft came to a quick end. But the major drivers of today’s debt crisis are Medicare and Social Security, and their price tags are set to keep rising. S…