You probably couldn't. But if you refer to two things Musk said - a) genetics is important, and b) PhD is not the best way to be useful - I think he didn't mean it to be taken together. He spent some time talking about how being useful means "area under the curve" - do a big thing for small number of people, or do a small thing for a large number of people. Most people can aim for either of the two, and in both cases PhD is probably not the most efficient use of your time.