In 1929, the oil tycoon Rockefeller was polishing his shoes on the roadside. The boy beside him said to him, "Sir, have you bought any stocks recently? I'll recommend one to you. It will surely rise well." Rockefeller was secretly delighted. A boy who polished his shoes began to recommend stocks to others. It seemed that the stock market was not far from a crash. Then, Rockefeller sold all his stocks. Two months later, the stock market crashed, and he spent the storm in gloom. There has always been a vampire law that everything will decline after its peak.