The only fiat worth holding are coins whose melt value exceeds face value.
Discussion
The raw material they're made from may inflate slower than the money supply but it still inflates faster than the Bitcoin supply. Especially in the long term.
So this may be true(ish) for now but what if Starship enables asteroid mining or if nuclear makes it practical to produce these metals in a lab.
What if there’s an EMP and every machine on earth is fried and coins are the only source of these materials readily available?
Just as implausible as your scenarios in the short term so what does it matter?
Haha good one.
Although, after such an EMP the coins value would likely surpass the melt value of the coin, so they wouldn't be worth holding?
How about this.
Fiat with value greater than melt value should be sold.
Fiat with value less than melt value should be destroyed (melted).
Hold as little as you can get away with.