The next ideas, as many others at money.lol, are based on Nick Szabo's writings.
Probably the biggest monetary flaw with metals is that they are costly to assay or validate, which has required people to trust centralized entities such as coin minters and banknote issuers. Said trust is often abused.
Another flaw of gold is its physical locality. It makes gold less secure to store and far more transactionally local, thus more vulnerable to politics and less sound than Bitcoin, that enables secure personal property ownership (through private key management) and seamless worldwide transfers (through its trust-minimized global settlement).
Aztecs took gold tribute from their subject tribes and amassed it.
Spanish conquistadors looted the Aztecs gold.
Sir Francis Drake and other English pirates looted their gold in Spanish galleons.
British stopped being able to transport gold during World War I and II because german U-boats were sending significant fractions of Allied and especially British boats to the bottom of the ocean.
Seizing gold vaults was an universal war objective.
Many politicians have controlled monetary systems by controlling gold.