Earlier quoted context omitted.
The notion that nation-state issued fiat currency is based “solely” on convincing others they have value is quite a reductive over-simplification. The existence of organized societies with some central government body has shown value, and the means of exchange amongst citizens and with citizens of other societies is backed in part by that value. It’s quite a bit more complex than you suggest.
The value of fiat currencies is "based solely convincing others they have value" - it is trust in the issuer. You are arguing that trusting issuers has been societal valuable, which sure - historically it has been for the fiat currencies that still exist (if you ignore survivorship bias). Not sure what handwaving "society is valuable and that value is what backs fiat currencies" even means in concrete terms. The gove…
You can continue to assert this, but that doesn’t make it true. And it is definitely not “hand waving” to make the observation that organizational structures provide value. Some more than others, depending on the context and time. Fiat currency arises out of the dominant current organization into nation-states, and the value is from the same root. It’s more or less an emergent property, not the directed efforts of some few elites to convince everyone else of the value. If and when this organization loses value, we’d likely see a similar devaluation of fiat currency. For example, a “mad max” apocalypse scenario.