Bitcoin is not stable because people are not enough confident in bitcoin we can see in investment people are borrowing more bitcoin but people are not enough confident in Their investment totally bitcoin is bit risk only so bitcoin is not stable.

People will sale bitcoin because of profit . In bitcoin selling bitcoin is major part when bitcoin market get hike the investor has to sell the bitcoin then only it will become profit even we cannot predict the market of bitcoin some time it will get down the market as well so, when price will get hike we have to sale.