They're relatively useless for other purposes. Eg, gold is rare, heavy and malleable. In situations where you need those qualities other options exist, like lead. It has the advantage of not oxidizing, so it makes for great jewelry.
But all of that is extremely contextual. If it turns out there's a huge reserve of it somewhere, it will crash in value. Or if things crash badly enough there may be other things to worry about. Eg, a community that desperately needs water is probably more interested in pipes than gold.
They (i.e. materials like gold/silver) have inherent value as being relatively difficult to obtain without significant work and being useful in creating valuable objects.
Because of those properties they become a store of value (representing the work and rarity) which then makes them a useful proxy for trading that value, which increases their rarity/value by taking it out of circulation when used as a store of value.
Because the community believes their value will outlast the currency system. People have believed the same thing about tulips, peppercorn, wine, and buildings (or rather, land).
Well there’s residual value in metals as you can build stuff with it. Agree that the vast majority of the value of precious metals is contextual, but I guess you can appeal to human’s love of shiny stuff plus history, beyond just community context.
But all of that is extremely contextual. If it turns out there's a huge reserve of it somewhere, it will crash in value. Or if things crash badly enough there may be other things to worry about. Eg, a community that desperately needs water is probably more interested in pipes than gold.