The problem with gold is (a) there is too little of it, (b) and as such it is too volitile for long term pricing. (c) and it is too open to manipulation.
The problem with the fiat money system is only (a) we don’t have enough types of money, (b) we pay interest on borrowing from ourselves to create long term capital (housing, cars, appliances), which makes no damned sense at all, (c) we distribute liquidity through the financial sector and credit rather than just directly to consumers (citizens), and therefore cause the entire economy to reorganize and suffer the shocks, rather than simply having consumers correct the shock by shifting of consumption and debt.
Libertarians are pretty much always wrong, because they’re always only half right, and they’re half right not because they’re moral, but because they want to enable private sector rents rather than public sector rents, instead of eliminating rents altogether.
No man has any right to appreciation of a currency at the expense of others’ reduction of consumption or production. There is just no way to claim that. But it’s exactly the purpose of (((libertarian))) dogma: restoration of “the rents of the pale.”