Money is fundamentally made up. It’s whatever the other party is willing to accept as a token that they trust will in turn be accepted by someone else they want a service or item from. Fiat currency just has its backing from being used in transactions with the state.

It also follows that the total value of global money is entirely dependent on people’s trust in it. The nominal value of global money supply, whether it is 1 quintillion USD or 100 trillion USD, doesn’t directly affect the worth I, or anyone else, ascribe to having 1 USD myself. It’s the things that I perceive myself to be able to trade that 1 USD for that do.

What I’m trying to say is that the philosophical idea you’re looking for might be more along the lines of “how much of their own resources (time and belongings) is the combined global populace willing to trade for a promise of trading it for someone else’s resources in the future”.