Bitcoin is alot, and its ALSO a collectible.
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.