Almost half of the world gold demand is for speculative/investment purposes[1]. If you consider jewelry to be speculative as well (at least partially, since if you only cared about appearance you could just plate it), the vast majority isn't "useful".
> Almost half of the world gold demand is for speculative/investment purposes
fair (and I think gold as a "beautiful" metal is dumb), but the other half of the usage (on your claim) is for an array of productive things. I don't see wires, heat reflectors, etc being made out of bitcoin.
[1] https://www.statista.com/statistics/299609/gold-demand-by-in...