All value is subjective and thus at the whims of wild animal spirits.

Gold seems stable largely because the price must rise to make mining significantly more of it economically viable. Yet, were it truly stable, prices measured in terms of gold should have seen price deflation from the Roman era to now. That this is not the case proves that gold has zero intrinsic value. It may have some inherent utility, but that is not the same thing. As people want more gold for use as a conductor, or in alloys for dental prostheses, or for adornment the price will go up. Speculative demand can make the price go up. Demand for trade without USD can make the price go up.

Gold and USD prices are independent of one another. That they can be used to measure one another is also a human invention and an accident of history.

All value is subjective.