To this day, the willingness of a Wall Street investment bank to pay me hundreds of thousands of dollars to dispense investment advice to grownups remains a mystery to me. I was 24 years old, with no experience of, or particular interest in, guessing which stocks and bonds would rise and which would fall. The essential function of Wall Street is to allocate capital—to decide who should get it and who should not. Believe me when I tell you that I hadn’t the first clue.