But, my question would be, while it is as you indicate, the US debt is constantly renewed, why would we not want it ever paid off or payed down to nothing over time?
I'm going to need to channel my inner Alexander Hamilton to answer this properly
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Your argument was the same thing that was presented by many of the founders including James Madison, which was that being in debt was a bad thing for a young, struggling country. Hamilton argued the opposite, saying that the country should have a national debt (although I don't know if he could even comprehend 10 trillion) in order to establish the concept of "the full faith and credit of the United States". That term is incredibly powerful today- if the US government says that XYZ has value of $100, and it guarantees it, then XYZ is worth $100. It's exactly how our monetary system works. Hamilton understood that by building up a debt and continuously making good on our interest payments would provide the US with the financial backstop to borrow more as time goes on, particularly during the rough times when we needed it. It's a bit counterintuitive to the way personal lending works where you generally have limits on how much you can borrow based on the collateral you have. What Hamilton sought to establish is a limitless source of borrowing for the US based on the fact that we have pristine credit and would never default.
The only way the US was able to get through WW2 was through our ability to limitlessly borrow. Debt/GDP was at 140% at one point, but the government was able to continuously issue war bonds to raise more money.
Pulling back to today, I don't disagree that the debt needs to fall somwhat based on the debt/GDP ratio- it should probably be in the 60% range as opposed to the 80% range- but nobody knows the "right" range. Wiping out the debt is silly, given that there's very high demand for it and investors see it as a safe haven. The government always borrows at the lowest rates on the market. If the government can borrow at 2% and then "lend" at a higher rate, it's always worthwhile to have debt.
Now, the deficit is a different story. We should try as hard as possible not to be running large yearly deficits because it shows that we are managing our budget poorly- either spending too much or not collecting the efficient amount of taxes (99% the former, 1% the latter).