When you decide to sell, be it today or tomorrow or whenever, chances are you will sell at the bottom. This will cause you massive depression, way worse than not selling at the peak to rebuy cheaper.
Buy and hold, or risk selling at the bottom and losing your position. After this dip stabilizes, we are going $2000.
If you do want to exit, sell a portion of your coins at regular intervals. You will average out your selling price then.
If you are a long-term investor, don't try to time the market by selling and then trying to buy bitcoins, Just hold.