It doesn't though. Go to your local Wal Mart, Costco, Home Depot, Target, etc. and try to make a purchase with it. Go to a local supermarket or restaurant and try to buy food with it. Stop at a gas station and try to buy fuel with it. Go to Amazon or eBay and try to make a purchase with it. Go to an airline or hotel website and try to book travel with it. Go into your Uber app and try to pay with it. Call your landlord and try to pay your rent with it. Objectively, it doesn't "work just fine as a currency" or we'd have empirical evidence of it actually being used as such in real life.