The TopCoder ranking shows very clearly that he developed a slump at the end of 2008 and in 2009.
According to another record, the slump period was from 10/27/2008 to 5/1/2010. I started reading Drucker around February 2010 and have been attending Tokyo Tech MOT since 2011. He felt a sense of crisis: “If I only had my expertise as an engineer, I would be in trouble if that turned out to be inadequate.” This slump should have been a strong reason for him to think about expanding into fields other than programming, but until he looked back on it this time, it was completely absent from his memory.
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