Successful currencies meet three criteria:
(1) they are in widespread use as medium of exchange
(2) they serve as unit of account
(3) they are a stable store of value.
Most sovereign currencies fully meet all three criteria.
What about Bitcoin?
well on number 3 i think its hardly toajntsin that kind of staff because of the volatility of the price in the market bitcoin cant easily attain on being a stable price. Any crytocurremcy id hard to attain that. As the investor getting bigger theres also will be a lot of changes on the price because of the holders and panic sellers. As theres an improvement on cryptocurrency the price itself cannot be stable.