so long as the leaving party takes their fair portion of the national debt and repays all federal infrastructure investment.

Who would accept payment for the "debt"? It simply guarantees the holders of bonds that US dollars will be created in the future to replace those that were extinguished to purchase the bonds. That debt represents our infrastructure investment, so it should be paid for twice?

Prior to the Federal Reserve Act of 1913, America had over 150 separate currencies, many with their own rate of exchange for the US dollar or gold value which fluctuated wildly. This was a nightmare for simple interstate trade, let alone the level of international trade Americans now engage in.

The one thing unifying America is its sovereign currency, even if it isn't understood correctly. Leaving the union would entail leaving that currency and its benefits to start an economy from scratch. That will be the Achilles heel of any politician advocating for such nonsense.