Mr. Mlodinow: I believe there is true expertise in some endeavors, and not in others. There is obviously no such thing as expertise in predicting the results of coin tosses, but there is expertise in predicting the behavior of lasers. I feel that picking stocks or predicting Hollywood hits is more like the former. The process of building a company or making a film is more like the latter.
But there is a related question: Given that we are discussing an endeavor in which it is possible, how can you tell if someone has expertise? That is hard, because expertise plus bad luck can equal a failure, and lack of expertise plus good luck can equal success. The only way to tell the two apart is to observe the individual over a long time, which in statistics often means 100 or even 1,000 trials. This is obviously often not possible, so I recommend instead that we judge people by a thoughtful analysis of their intelligence, philosophy, work ethic, etc., rather than simply by their results.