Everyone will incur loss at some point in time. There will be paper loss and actual loss. If the stock is good and still have money, buy some more shares at much lower price like Charlie as we read about double his stake in Alibaba. if stock is lousy, one can choose to cut loss by selling away. Rather than look at the paper loss that emotionally pain you for many years. Even if u suffer actual loss on a stock counter in time, you may come in and pick up when it goes much low...