There is no way that the prices of bitcoins fall the way they rise up, because the prices start rising about one year ago. In start the prices start maximizing at very low ratio like 1$ per week and sometime 2$ per week but now its price increasing as 50$ per week. So it’s not possible to fall down the prices of bitcoins. Even if they start falling the holders have much time to sell bitcoins and get the money of higher price according to their expectation.