In terms of investment, I'm choosing bitcoin, but for the regular transaction, we cannot deny that fiat is more widely accepted compared to bitcoin, so we cannot just ditch fiat for bitcoin because it will not happen. The majority are still using fiat, and I don't see any possibility that bitcoin will surpass the popularity of fiat in the future unless we will shift into a decentralized world or government.
People are paying widely in fiat for their local purchases but many people like others to accept bitcoin for their purchases but they cannot because the retailers are not aware from this much and they do not accept right now. For international purchases crypto is used by people on all those platforms where it is accepted and people are happy with it.