Fiat currency doesn’t work like that. It is a way to hold value so that a potato farmer isn’t exchanging a bushel of potatoes for a dentist appointment. It still needs to be backed by productivity in the economy, otherwise you just get hyperinflation. There is no magic.
And between every dollar being backed by a bushel of potatoes or a dentist appointment and hyperinflation, lies a vast gap of other possibilities. For example dollars backed by future productivity that people believe will materialise which doesn’t exist today. If you factor in debt and look at fiat as a form of debt it should become more obvious why you can create money today that enables people to do work which they otherwise wouldn’t, without causing inflation, let alone hyperinflation, under the assumption of available real resources (labor, tools, metal, land, knowledge, etc).
