Public debt is more like a brake that gets worse and worse really slowly over time.
And then it suddenly explodes - more and more of the budget goes to interest payments instead of procurement.
At one point the government has to borrow to make payments on the debt, and then you’ve got a very bad spiral.
Because the debt is in US dollars, the government will inflate away the debt. So the end game is dollar devaluation, followed by enforced budget discipline because lenders will no longer accept treasury bills.