The pair of socks I'm wearing right now is pretty rare as they are one of a kind but that doesn't make them valuable.
No, what makes it valuable right now is the possibility that a lot of people in the future will desire it as a store of value.
This isn't even mentioning how bad of an idea deflationary currency is as an actual currency.
The market prefers commodities that are both scarce and durable to act as money, all else being equal. Bitcoin manifests these properties even more perfectly than gold. You can argue about the macro-economic effects, but in the end, it's what the market will choose if given the option.