Now just look what people pay for magic cards or baseball cards, stamps, old hardware, whatever, if its rare, there are people "hoarding" it
Currency= a system of money
Money = store of value, medium of exchange, and UNIT of account.
Unit's are definable in objective terms and are a constant. Bitcoin is not a UNIT so it is not a UNIT of account.
It isn't currency.
What is a definable in objective terms and is constant. Nothing is constant. What I'll charge for my time isn't constant, what you'll charge for your time isn't constant, what I'll charge for gold, silver, copper, bitcoin, lumber, corn, or armchairs isn't constant.
That doesn't work as a definition for money because money by definition isn't constant, its affected by the money supply & money volatility, neither of which are constant. Its also affected by people's psychological want for that form of money.
A unit of account is any method of expressing the worth of account. In other words, I can't use armchairs as a unit of account because 3 armchairs doesn't mean anything to anyone. 3 Bitcoins, however, does, because it means something somewhat standard to most people.