A lot of things can be attributed to this. First of all, bitcoin, just like other digital currencies, was created in a decentralized way such that it is not controlled by the entity. This means that the price of bitcoin depends mostly on the activities of the investors. One of the things that are causing the price of bitcoin to fluctuate is the increasing rate of bad news, records about bitcoin. When people start doing this, it increases doubt and fear in people. And as a result, investors will be very unwilling to invest.
The fear that bitcoin may be regulated by the government is another thing. Most investors think the involvement of the government will definitely affect their investment. Competition is also another factor. Aside from bitcoin, there are other cryptocurrencies like ethereum, peercoin, litecoin, etc. Any form of competition between will only lead to the reduction in the prices of some digital currencies, while others with great visibility will have their prices increased.