Those who are fretting and spreading fear over the national debt need to take a basic accounting course to understand it better. Banks and business universally use dual entry spreadsheet accounting methods to track money worldwide, and that method would show that every entry in a "sector" must be offset by equal and opposite entries in other sectors.
The national debt is merely an accurate accounting for money created by Congress that hasn't been collected as a tax payment, the accumulation of deficit spending since our nation's founding. It represents our "money supply" obtained from payments made by government for real resources and labor deployed by our government, not an obligation the taxpayers are on the hook for. (In proper context, a "balanced" budget represents theft of those resources and labor.) It would be more accurate to think of it as our "national savings" since most of it resides in Treasury bonds that guarantee interest dividends.
Treasury bonds are not a "funding mechanism" for spending by Congress. The US dollar is a sovereign fiat currency that is self funding when it is spent into the private sector in the form of reserve payments at the Fed. These payments are the sole source of net US dollar denominated monetary assets and can only be converted into bonds or used to pay tax obligations. Otherwise they sit idle or are used to pay obligations also denominated in US dollars.
It is only reasonable to expect holders of excess dollar reserves to invest in bonds to gain some return, and those bonds don't care who owns them when they mature and are converted back to reserves in the owners accounts. Other countries either gain reserves from doing business/trade with US firms or they convert other currencies to US dollars to pay obligations or invest in our Treasury bonds. All reserve and bond activity is contained within the US Fed and Treasury system.
As the sole monopoly issuer of US dollars, Congress never "needs" our dollars to enable its spending. There is no "infinity+1" in math that would provide Congress with more spending ability via tax collections or bond issues. It simply needs us to need them so it can provision itself without requiring a revenue stream. Since one cannot collect or borrow what doesn't yet exist it is more accurate to state that spending by the federal government "funds" the debt rather than the other way around.
