Well no fiat is still better than cryptocurrency in every other way. because of this reasons.
1. Fiat can be used everywhere even without internet connection unlike cryptocurrencies
2. Cryptocurrencies especially bitcoin are slow than any payment methods it must have to wait 10 mins in order to confirm the transaction.
3. Most of the shops and store isn't adapting bitcoin so, it will be hard to find a shop to buy with bitcoins.
Let me quickly buttress on some of the points you have raised. You are right in a way but you still have to consider the positive parts too.
1. Sure fiats can be used everywhere, but that does not mean things are not gradually going digital with even the fiats. The population of people holding fiats now are hugely dropping and most people are now using mobile system for their transactions. I am not saying crypto will take over fiat completely, but we will have a time that making transactions with crypto will become so easy.
2. Cryptos does not have to wait 10 minutes before it gets confirmed. Bitcoin is just one of the cryptocurrencies as some other altcoins are pretty fast. However, I made a transaction yesterday with bitcon and funny enough did not take up to 2 minutes before it gets confirmed, so all still balls down to your tx fees.
3. It is hard now, but it is still a start and we cannot use that to judge yet. One day, bitcoin will go mainstream and we will eventually see how much it pays making transactions with cryptos.