If it started to reach the point where the government was printing extra money to service the debt, we would be in trouble. But we're far off, partly because there is also tremendous global demand for US dollars as a reserve currency and de factor international currency across the world

And the largest holder of US debt is ... US citizens, investing their money in the single most stable and risk free investment to spend it in the future.

The only concern is when the cost of servicing the debt (ie interest payments) becomes too high that the government struggles to pay for services.

Confucius say, it is better to shit your pants, then never shit at all