Buying wrong is more serious than selling wrong. Once you confirm that you bought wrong, you must act decisively and let the chips go to hell. If the market gives you a chance to correct your mistake and you don't take it, which is the second type of buy/sell point, then just buy tofu and go home; if the market gives you a second chance to correct your mistake and you still don't take it, which is the third type of buy/sell point, then just go home and grind the wall.