Cryptocurrencies are securities not money. Unless you have force (army) that enforces your money you will not have money.
Sure cryptocurrency is not as widely accepted online or in person locally as US dollars, but it is far easier to spend those same places than my Euros which actually meets your definition of money.
A medium that can be exchanged for goods and services and is used as a measure of their values on the market, including among its forms a commodity such as gold, an officially issued coin or note, or a deposit in a checking account or other readily liquefiable account.