Has anybody here read "This Time Is Different: Eight Centuries of Financial Folly"? by Reinhart and Rogoff ? Sovereign defaults are the rule, not the exception, if you look across long periods.
What I remember from the book was that borrowing is easy. Investors believe a gov't will always repay its debt. Interest rates are low. The gov't can fund things the gov't (or the citizens) want to do without raising taxes. That's always popular.
The debt builds, but confidence doesn't lag. Investors figure they are smart enough that, if things look bad, they will notice and get out before others catch on.
Then something happens and everyone rushes for the door at the same time. Interest rates spike, the gov't can't refund debt except at punishing rates, and it ends up defaulting. This causes great pain to the populace, especially people who had been expecting something from the gov't, like a pension with purchasing power.
The US wouldn't need to stop repaying loans. It can "just" print money to cover them. But, with $26 trillion in debt and maybe $2 trillion in circulation, the amount impact on prices is huge.
I'm thinking I'll be dead before that happens in the US (I'm 73). I don't have any good advice for my kids.