I developed this intuition for myself that I think kinda works. I think of govt debt a bit like stock investment in a large corporation. People "put money" in it because they believe it delivers returns and will keep delivering returns. And as you said, this is actually much easier for the government to do than a corporation as simply the fact of releasing the money into the economy generates returns. So instead of thinking about the size of the debt, one should be thinking about the ability of the government to function well. Ironically, it seems like this is also the way the market looks at it. It keeps throwing money at it and it only knocked off its credit rating due to the threat of dysfunction around the debt ceiling.