Nobody can accurately predict the tops and bottoms of stocks. If a trader is trying to do that, he is just trying his luck. Trying one’s luck in trading is an EXTREMELY RISKY business. In the long term, the odds are against one who does that.

True Traders do not attempt to buy at bottoms and sell at tops. They will sacrifice part of the move as insurance premium, in exchange for an increased probability of success. They will not risk their capital for trying to make/save that extra premium/gain.