The main reason for bitcoin being so volatile at that time is simply because of the fact that it was in an extremely bullish market, then the market sentiment simply went completely bearish, meaning that prices dropped significantly.
This is natural for any asset, including bitcoin. The period in between bull and bear markets have actually gotten a lot less volatile and extremely stable.
Of course, there are other reasons, such as the fact that there is no one regulating the price of bitcoin since it is decentralised and traded on the open market, as well as the fact that we're still in the early adopter stage mainly.
Volatility can actually be a good thing, don't view it as something that will necessarily hinder the growth of BTC at all.