That’s true but the belief that gold has cosmetic value goes back for thousands of years. Even if you ignore that something like two thirds of consumption is industrial, that’s a huge track record to conflate with … basically nothing. It’s on the scale of saying there’s no reason why your band couldn’t be as valuable as the Beatles.

There's plenty of stuff more expensive than gold, the reason gold is used is because it's shiny-bling.

People in the past have traded using seeds as fiat, but they wore shiny or coloured things like shells, polished stones, polished metals.

Human vision is attracted to shiny and brightly coloured artefacts, it's not entirely subjective. This is why you can trick a child to accept a shiny coin in exchange for a high value item, or currency note, or even for a higher value coin that has less polish.

All value is defined in relation to a specific person. There's no movie, for example, that everybody likes. But that doesn't mean that entertaining people isn't valuable.

There's still a difference between use-value (looks pretty, albeit subjectively, to you) and exchange-value (looks resalable, albeit in your estimation, to someone else). There's a difference between what you want to do with the thing, and what you can do with the thing yourself, without someone else with whom to transact.