Bitcoin is a decentralized entity, in which no one can manipulate its operation and wherein its value only depends on how the market goes. Bitcoin, follows the rule of supply and demand in which its value increases as its demand increases because of bitcoin's limited supply. Price changes in bitcoin is always due to some external factors, like its market as mentioned above, and the infrastructures surrounding the bitcoin community. Just like in some other form of investments, its value loses when investors pull out their assets.