Um, go back a few decades and make the same point about the U.K. ...
Just because the U.S. is at the top of the heap at the moment doesn't mean that they can't spend like drunken sailors.
Time to tax more, spend less, default or some combo of the three. Seems like inflation (sort of like a slow default) is the preferred, and potentially very dangerous in the long-term, option. But I think the wave of boomers will require a bit of the first two soon enough.