The national debt held by the public tops $27 trillion. It’s bigger than the entire American economy.)—and it’s on track to grow faster and faster. In just four years, Donald Trump signed legislation that increased future debt by $7.8 trillion, more than George W. Bush and Barack Obama managed in eight years apiece. We’re headed for an economic catastrophe. So when Trump made an appearance late last week at PubKey, a bitcoin-themed bar in New York’s Greenwich Village, Reason’s Nick Gillespie went down to ask him about it. And he had a snappy comeback. Less than half of Trump’s new debt was rel…