Bitcoin is not a currency. Bitcoin is a wrapper FOR the value of currency that allows that value to be transferred anonymously and verifiably and then re-transferred to currency. That's cool - and dangerous and so will eventually be banned - but it is what it is, a way to transfer value, not to store it (any more or less than any other speculative asset - i.e. not as money) or tokenize it for later use.

Of course, a transfer token MAY be used as money if it there is no need to unpack it into local currency. But generally, only a stable token will pass that test. That's why, when stablecoins achieve the reliability of the BTC network, stablecoins will supplant BTC, and a stablecoin may become a reserve currency. But since the stablecoin will almost certainly be pegged to fiat, it is unlikely to represent an advance over the fiat it represents. (Stablecoins are to money as gold certificates were to gold on deposit all those years ago.)