Many people prefer fiat who don't know the uses of Bitcoin or other crypto, only those guys prefer who knows that bitcoin is the future currency.
But Fiat is on top because if we want to buy things then we have to pay in fiat, not in BTC but if btc accepted in stores then we can say that in near future btc will beat fiat and huge amounts will send in BTC. Fiat sending fees is very high even that btc will charge few dollars for huge amount.