Well, if you look at the volatility of bitcoin in particular, you'll see that it is decreasing pretty steadily. The first big bull run was very significant, 1000x, whereas the last bull market was only about 100x. The current one who knows, but it's looking like it will be about 10x. This volatility is a part of the price discovery process for any new asset class.
Fiat currency may appear stable, but it is not. It appears stable because it is used as the unit of account for all other assets in a country. In the long run, any freely floating asset will be more stable than any fiat currency managed the way modern ones are managed, via a central bank, provided that the supply change of that freely floating asset is predictable. Gold, for example, has a supply increase that is predictable. Central bank controlled fiat currencies are by definition not predictable in their supply, and this makes assets that are more suited to saving/investment, regardless of short term volatility. Nobody can empty your savings into their own pocket by printing gold or bitcoin.
Fiat currency may appear stable, but it is not. It appears stable because it is used as the unit of account for all other assets in a country. In the long run, any freely floating asset will be more stable than any fiat currency managed the way modern ones are managed, via a central bank, provided that the supply change of that freely floating asset is predictable. Gold, for example, has a supply increase that is predictable. Central bank controlled fiat currencies are by definition not predictable in their supply, and this makes assets that are more suited to saving/investment, regardless of short term volatility. Nobody can empty your savings into their own pocket by printing gold or bitcoin.