> How do you avoid eventual hyperinflation when you keep borrowing more and more money to increase your debt even more?

if i understand correctly, from reading bits here and there, its basically as long as you have something to offset the printing with (taxing out of circulation, ensuring the excess money is spent, taking out of circulation with bond offerings etc) then the "negative" value of the taxing/spending/bonds prevents the in-circulation (positive) cash to cause inflation.

its basically the debts vs liabilities balancing each other out on a national scale: as long as you balance the assets with some kind of liability, you are 'ok' afaiu

basically, modern monetary theory*

* https://en.wikipedia.org/wiki/Modern_Monetary_Theory