At our current rate of spending, the U.S. will be unable to confront major problems in the future because we’ve already stretched ourselves too thin.America’s debt and deficits usually are spoken of in terms of economics, but they have huge implications for national security. To see why, start with the economics angle. Famed investor Michael Burry — who foresaw the housing market bust and was played by Christian Bale in the hit film “The Big Short” — has just issued a warning. In a series of tweets, Burry said that the stock market could crash because of too much debt....