The final cause and also the most obvious cause but Bitcoin price dropped the most, this is the psychological sell off from investors. Young trader and inexperienced trader easily fall into panic when the market shows signs of decline, followed by a wave of selling off and the situation becomes worse.
It seems like there is a game of big traders, want to create a panic situation, and the effect that occurs is that small traders will quickly sell, this kind of thing that big traders really want with the panic caused will decrease the value of the currency,
and the big traders can buy in large quantities at a relatively cheap price, tricks like this have often been done in the world of commerce.