i dont think cryptocurrencies are better because they can not work offline and transactions are not very quick like they are in conventional money. moreover,transactions charge high feesBTC which makes their use impossible for small transactions.
Cryptocurrencies have limitations I do not think that anyone is blind to that, but cryptocurrencies also have a lot of good things going for them, the most important aspect is decentralization since that allow us to be the owners of our bitcoin, that does not happen with fiat, even if you have a dollar bill in your pocket, it does not belong to you it belongs to the federal reserve.