There needs to be some basic economics here.. Money has value because of the value of the economic transactions in which its conducted. Government-backed currencies are forced to have value in the sense they force people to use it for their taxes. The US, additionally, forces the world to use it for oil trades. Value is in those economic transactions. A currency is just a "liquifying" of that value, to make it easier…
I really don’t buy the old taxes-make-the-money-work chestnut. Far too many counterexamples.
No one facing a hyperinflationary death spiral says "oh well, at least the government will take taxes in this crap" they desperately cast around for a stable place to put wealth.