I would argue that your examples are about manipulation of people, not of the currency. Similar to the craziness of the GME (Gamestop) era, where it felt like everybody and their dog started buying GME stock. Or, say, a news outlet causing panic and a bank run. Though you’re right that since crypto still doesn’t have broad adoption, it’s easier to manipulate the smaller userbase.

Manipulation of the currency would be more like the government printing more money. This is not possible in crypto, where power is decentralized.

The instability is definitely unfortunate though. It’s a chicken and egg problem. If crypto had wider adoption, and was accepted in many stores, then it would become more stable. Just look at how much more stable the big crypto coins (bitcoin, eth) are compared to smaller altcoins. However, due to low adoption it’s still quite unstable, and that instability hurts adoption 🙃