Bitcoin price is also not stable.
What can you expect with a coin that's decentralized and isn't controlled by the government?
Crypto isn't stable because there aren't enough people in it, it's that simple.
You just can't compare the amount of people trading BTC vs the amount trading EUR or USD.
And BTC, still being at the top, is still the most stable crypto (which, again, does not mean stable, at all). Those who are saying that ALTs are more stable, are probably very new.