Yeah, that's the issue. Hyperinflation usually involves large increases in the prices of basic necessities (food, utilities, gas, physical security, and shelter if you don't own your home) and collapses in the price of financial assets. Except for the most hardcore leanFIRE types who are into subsistence living off the land, that's usually levered the opposite way from most retirees.

Being able to count on your own labor and having skills in industries related to fundamental survival are key in hyperinflationary economies. You can't count on the financial system remaining intact in any usable form. Most FIRE plans are about leaving the labor force to live off of returns of capital, though.