It's worked for gold and diamonds for generations. Not to mention pretty much every artwork or other concoction human beings create and then collect.
There's not a lot of cash flow from first edition Marvel comics, but there are an awful lot of them stored in plastic bags.
Humans collect and value all sorts of stuff for no good reason. Cryptocurrency is no different.
It becomes even less of an issue when you realise that we all create 'currency' all the time. It's just an embodiment of a promise to do something in the future. Far more of a unit of account than a thing.
The trick is getting other people to accept your currency. Which is a lot easier when you can impose coercive charges on people denominated in that currency - whether that is a tax, or a tithe.