These currencies, as they like to call themselves, will only become stable when there's a basket of goods you can exchange them for at a consistent price. Right now it's all speculative investing and a little bit of spending as a currency.

Once you can buy $10 of goods, consistently, for 0.0001 BTC (or whatever) then the price will be stable and the currency can establish itself.

The same is true for the other cryptocurrencies. Being unpegged from any other currency or any goods, and nearly useless for conducting business transactions means the value will remain wildly unstable with a significant non-zero risk of failure or effective failure (going to $0 or something not much above that with little interest in conducting business using the currency).