You don't want to sell too early, because you miss out on profits, but you don't want to wait too late to when everyone else sells, triggering a crash.
你不会想过早的抛售，因为这样你有可能错失很多利润 但你也同样不会想等得过晚， 以至于等到每个人都抛售了，引发了股市的崩盘。