One interesting thing about the federal government's debt is that it behaves very little like an individual's debt.
A pretty decent 10-year student loan right now is at 4% interest. And you generally have to pay it back with actual money that you earn.
A 10-year treasury note is at more like 1%, and nobody bats an eye at the government covering payments by issuing more notes. Meaning that, in effect, the US government is getting an indefinite interest-only loan at a pretty low rate.
Actual humans don't get to do that because of a sticky problem: eventually we age out of our money-earning years, and (hopefully some time later) we die. Lenders, understandably, have an interest in getting their money back before that happens. Or at least in getting to the point where the loan is collateralized by assets that are worth more than the loan's balance by the time that happens. And that's the ultimate reason why revolving debt gets worrisome: It's running down the clock.
The US government, on the other hand, is theoretically immortal. There's a risk that it might become insolvent at some point in the future, but there's not the same reason to worry about handling debt by endlessly revolving it, because there's no proverbial clock for it to run out.
