I think the rapid dropping of price is due to some people that until now still selling their bitcoin in low price because they want to cut their losses due to continous fluctuation of the almost all cryptocurrency in the world market.
Its true the reason why the price of bitcoin is rapidly going down because a lot of people starts to sell their bitcoin in low price, that is why the price of it continues to decrease. Another thing that makes bitcoin price falls down because of banning bitcoin in other countries that it starts to lose its investors.