I sometimes wonder whether the fiat money system wouldn't unravel in a confidence crisis if ordinary people abandoned the money as a thing metaphor.

I think it wouldn't unravel. I have spent some time in my youth doing live role-playing - i.e. running around in the forest dressed as an elf or an orc and fighting others similarily attired - and those three-day worlds generally comes with a currency, often dated but common coins. The inflation rate tends to be staggering, in particular as the participants does know that the world is coming to an end. However, it is easily remedied by oputting the currency on a de facto mead standard by having the inn (got to be an inn) having a set price for mead in in-world currency.

In a similar way, I see our fiat currencies backed up by a de facto stay out of jail standard, that is taxes. So any crisis of confidence could promptly be broken by taxation to yet again impress the very real value of having enough money.

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