I agree that the reason of the fluctuation of bitcoin is the decentralized system. We all know that there is no body that regulates bitcoin meaning anyone with capacity and capability can manipulate it according to their likings. Aside from that, bitcoin is susceptible to speculations of investors that makes it highly volatile.
Price fluctuations, but indeed a bitcoin I bet that the price of bitcoin no regard to investors who are interested in bitcoin. Because the existing investors in the bitcoin does not have any policy or the correct strength inside. So if an investor is associated as the person who controlled the economy of bitcoin, then it's all not true. Bitcoin nobody mastered and could only give a good effect is mining, without mining bitcoin will not be able to walk normally