I think the biggest reason that can make bitcoin price volatile is trading activity. If we compare it with fiat then we can see big difference in volatility. In my point of view, this is caused by the percentage of money that used for investing or buy goods is bigger than money that used for trading. Maybe it is because most of bitcoin users are trader so they cause volatility to create opportunity to gain profit. But I think it's not a problem because it is one of many factors that attracts people to invest in bitcoin. I think when most of people use bitcoin as currency rather than in exchange site then the volatility will be decrease a lot.