Overcollateralized stablecoins (like DAI) are not volatile and they are in the category of cryptocurrency. So they do change that. The change is slight, but ever-growing.

BTC's price itself has grown much less volatile.

> the volatility spikes in Bitcoin were most extreme in 2011, with subsequent spikes in volatility lessening over time

https://bitcoinist.com/looking-at-bitcoin-volatility-over-th...