Why aren't Americans more worried about the national debt?

>America lives beyond it's means, the national debt is currently 33tn dollars & growing all the time. There is no realistic chance of any of your political parties changing this which seems crazy, to me it seems like the biggest 'risk' to the USA (at some point) is your financial position, you have to pay it back at some point. The US possesses the single largest economy in the history of Humanity. Our wealth makes both the British and the Roman Empire at their peaks green with envy. On top of that, the US has the most powerful ground army, five of the largest air forces in the world, claiming the first and second spots for ourselves, and the largest navy in the world. Who's going to make us pay it back? The US will pay the debt on it's own time, and there is not a single country in the world, or even a coalition of countries, that can force the US to pay it back outside of our own time. The world operates on the American clock, not the other way around. The US simply operates on a completely different plane of existence in regards to money. Even our closest competitor, China, can't match us in the sheer amount of money and debt we can take on before it becomes a serious problem.