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the thing that you must know is that manipulating the price of bitcoin is very difficult, you have to have it in large quantities whereas currently only a few people or groups have a lot of bitcoin, so that in the future even though people continue to trade bitcoin the price will continue to be volatile and difficult to manipulate.
As bitcoin becomes more popular and larger, price manipulation may become more difficult. Given what's going on, bitcoin is still a very small cap, so manipulating bitcoin price is hard for retail investors but for sharks, it's too easy for them. Sharks, market makers, cannot manipulate the bitcoin network, but price manipulation is what we see happening. If the price of bitcoin moved according to supply and demand, there would never have been such large fluctuations. All financial markets have manipulation, but with bitcoin, it happens more because it is still small, without any regulation.