Cryptocurrency exchanges and trading are practices where two people can oversee your transaction outside government oversight. In countries where the national currency tends to fluctuate constantly, causing the quality of life to plummet, cryptocurrency can help to avoid these economic disasters
National currencies (fiats) have inflation or hyper inflation but they are not printed at similar rates of Terra minting for their tokens, $LUNA and $UST (a failed algorithmic stable coin).
Because you say about cryptocurrency, I conclude fiat currencies are better than cryptocurrency about price stability.
Bitcoin is unique and better than altcoins. It is decentralized, can not be minted more any time by altcoins, tokens. It is better than fiat currencies too because it has only 21 millions in total supply and it is less inflationary than fiat currencies.