Bitcoin stability isn't that important, the instability is the strength of Bitcoin. We all knew about the instability before we decided to buy Bitcoin. The instability didn't stop us from investing in Bitcoin so it isn't a problem. It's the instability that make Bitcoin attractive to investors. Some set of people see the instability as an opportunity to trade Bitcoin to make profits. It's the instability that make the currency won't investing into for now because the other features isn't yet an important part of the currency (speaking about the means of payment part of Bitcoin).
Bitcoin doesn't need to be stable for it to be accepted asa means of payments, if Bitcoin was to lose it's characteristics of instability then it'll lose it's identity and would just be like other fiats. The high interest in Bitcoin has a lot to do with the fact that many people see Bitcoin as an asset to increase and stop their wealth.
There are more important things Bitcoin needs to tackle like the high fees, amount of transaction it can handle per block and the delay in confirmation. Bitcoin needs to be accepted as a global currency by more companies and merchants to establish its stand as a currency. Stability isn't the least problem of Bitcoin as we have to accept it the way it is and see it's instability as its strength instead of a weakness for Bitcoin.