I think that after such rapid growth can happen a big accident, even up to 1000. Therefore, some of the coins sold to make a profit.
How can you say that bitcoin price is a rapid growth? Its not a bubble if you think it is. There is a lot of buying specially in the Japanese market. They are now having 50% of the total volumes of trading. But if ever there is a crash it will not go below sub $1000. Because the Japan impact is not fake unlike when Chinese keeps pumping the volume of trading that the Chinese government stepped up to stop their fraudulent practice.