I don't think I've ever seen a convincing argument that the physical "usefulness" of gold is a significant factor behind its market value. The closest is the argument that it's useful as marker for indicating wealth/status/privilege, because of its rarity (and obviously the skill involved in crafting it into various ornaments/utensils etc.). But yes, arguably more useful than cryptocurrency (where there's value in the concept of a distributed cryptographically-backed ledger, and the software that exists to support it, but not really in any individual unit of a cryptographic currency). Then again, there's really no absolute utility in units of fiat-issued currency either - it just happens to be the only sort of currency that governments accept for paying taxes (therefore necessary for keeping yourself out of jail).