Because sometimes K moves very quickly, and when short-term gains reach 500 points, I close the position. If I don't check in time, it can run away by several hundred points.
Based on the daily K-line trend of Bitcoin, it is expected to drop to around 84,000 in the next couple of days. Just find a high point tonight to go short. If you're feeling itchy, you can open a small short position now at 87,450.