@isaackuo @nyrath
Which is the idea in my setting...
Extra-cis-lunar settlements have to make due, after Earth gets knocked out of commission for a time thanks to an artificial local killer (250ktonne lighter meant to transport material to an orbital factory) being deliberately made to hit Beijing. This leading to a three way civil war in China, the other space nations locking up cis-lunar space tighter the a rats ass, a limited Kessler cascade destroying one of the Orbital elevators, and on top of that one hell of an economic crisis that lasts for decades.
So a commodity currency is a quick and easy method to get the space borne economy going again after the period of immediate survival.
Though that doesn't mean that they won't switch their currency to a fiat one after a time.