Bitcoins price depends on the demand of the market. If the bitcoin is limited, the value goes up, if it is many the value go down. Just like the rule of economics, the more the product is in demand, the value goes up.. If its not in demand, the prices go down. It is also like a gold, as time goes by, it's value rises.
Most of the investors are still unable to identify the reason behind this much of the downfall in the market value of the bitcoin as well as the rise in the market value of the bitcoin which we have experienced in the last year. The most important factor which effects the market value of the bitcoin is none other than that of the demand of bitcoin in the international market as the principal which is being used is demand and supply.