There are a lot of factors influencing the price of bitcoin, including technical issues/new alts coming out/regulations/stubborn miners/conflicts between developers(or groups)...etc.
What do you think is the most crucial cause? Why did the price drop dramatically these days? Will this be a rebound point?
In my own point of view, the reason why the price of bitcoin dumps dramatically these days is because of banning of bitcoin in other countries that the number of bitcoin users are starting to decrease that will affect to its price. I think the reason why pther countries banned bitcoin is because they are afraid that bitcoin will replace everything.