The reason the national debt is so large is that it represents all US dollar denominated currency in circulation. (All deficit spending of Congress in our history + Treasury bonds + interest on those bonds) Considering that it funds the world's largest economy and much of the world's trade we can only be thankful it is as large as it is.

Every dollar the federal government spends is a brand new dollar and becomes someone's financial asset in the private sector. What it collects back n taxes is canceled by the accounting entity of "debt" and is not able to survive past that to "fund" anything. It is "uncreated" the moment it moves from the private sector banking system into the government sector.

That is because it is, at its core, nothing but a promise of a tax credit that will always be worth one dollar of tax payment. Whatever remains in the private sector is our money supply that is able to net retire private sector bank debt or be net saved as Treasury bonds. It also represents the net payment the federal government makes to the private sector for the resources and labor it demands.

A "balanced" budget makes no net payment for those and effectively steals both, but hey, it will always be the holy grail of pandering politicians because they know 99% of Americans are econ illiterate and conflate the finances of the monopoly issuer of the nation's currency with their own.