Technically there’s no ceiling and as the reserve currency the us used to have special place, but there are consequences, there is “too high”, there can be a spectacular crash when other countries and currency traders get worried about whether you can pay it back. It’s just not clear where that will be.

US debt is now at proportions that has caused economic crashes in other countries. More importantly, payments toward that debt are now one of the biggest parts of the annual budget, making it tougher to afford other things