Yeah, sure, but everyone except cranks who works in fiat openly acknowledges that. Fiat (well, major fiat currencies like the dollar) are good for low-volatility liquidity. For long-term accumulation of value, you invest in productive assets, which are both riskier over the long term and higher volatility over the short term, but have higher average long-term yields. And, ideally, you diversify investments in ways that maximize independence of at least long-term variation, to mitigate risk and get closer to consistent long-term average results.

Crypto“currency” that isn’t fiat-pegged tends to be worse than major fiat at the things people who prefer fiat think fiat is for, while (in the best cases) being a very high-volatility speculative asset with very good average performance over its history to date (which isn’t very long term). It’s thus not a great replacement for fiat, but potentially a bice addition to the stable of available investments.