The appeal of metals is that value is global; paper money and Bitcoin value can disappear with the stroke of a pen or the push of a button. That ounce of gold has value (even if it is just $50) anywhere in the world.
As white people planted flags around the globe, many colonized people refused to take paper money; in a practical sense, it was expensive toilet paper. They would accept gold and silver coins, however - didn’t even matter whose face was on it.
And still is in some of those countries (e.g. Zimbabwe), except it is the indigenous people, not the white colonists, who are printing it.
Actually it would need to be many button pushes. If the US govt were to decide the dollar is worthless they could theoretically push one button. But there would be some residual momentum as people would still gladly give up their Venezuelan dollars for US dollars to trade for food since the farmer would still take them and not the V$. But the world would slowly switch to something else.
In the case of bitcoin there is nobody in the world who can press a button. All the miners (or 50% plus one) could potentially do that, but so far they haven't. It is too lucrative for them. The exchanges that will turn your bitcoin into "real" money and wire that money into your account make fees on doing that. They could all be shut down but again that is many button pushes.