We are told that crypto is supposedly a way to "stick it to the man", to fight those "evil banks/governments".
The trouble is that unlike fiat currency, there is no fundamental means of valuation. Crypto is worth what its worth on the day based largely or exclusively on entirely non-economic valuation, which is why its so incredibly volatile.
The trouble is that you cannot escape the truth that the world is based on trade. People make goods, people supply services and other people buy goods and buy services. People also buy and sell essential commodities. This happens both domestically and cross-border.
The value of fiat currency is ultimately tied to the economics of global, and therefore provides an objective means to value said currencies, both themselves and relative to other currencies.
You don't get that with crypto.
Well, you could argue that you do to a limited extent, but that limited extent would only make crypto comparible to emerging world fiat currency of some tiny country.... high-frequency boom and bust cycles, high volatility, potential for episodes of illiquidity etc.