many people selling their bitcoin if the price increase because they want to make a profit and they can buy again if the price is down. with the volatility of the price now, they can expect to make a profit by buying and selling the bitcoin and I am sure that if they can analyze, they can find a good price to buy and decide a good price to sell later. we can take this as our chance to make more money but we still are careful to not buy at the high price.