At the annual meeting of his Berkshire Hathaway Inc. he again pressed the argument that, in aggregate, investment professionals aren’t worth their fees -- and that people would be better off sticking their money in a low-cost index fund. He also challenged how hedge fund managers are paid. "If you go to a dentist, if you hire a plumber, in all the professions, there is value added by the professionals as a group compared to doing it yourself or just randomly picking laymen," Buffett, 86, said. "In the investment world it isn’t true. The active group, the people that are...