Rather than going into history (I haven't the time) or musing on the impact on his professional development (I haven't the interest) I'll just quote:
It's a topic I want to explore more as I mentally gnaw on it, but fundamentally I think that Steve Martin hit the nail on the head, and succinctly. An expanded version comes as the subtitle given to K. Anders Ericsson's feature in the Harvard Business Review: "New research shows that outstanding performance is the product of years of deliberate practice and coaching, not any innate talent or skill." Of course HBR turns it into a mouthful.
Be so good they can't ignore you. — Steve Martin
Part of the reason I've been mulling on this is because, as I've come towards the end of my blistering eight-year bachelor track, I've wondered about where to go when it comes to a career and what to do once I'm an eligible bachelor on the prowl for employment. The standard line for years and decades has been to follow one's passion, but then the problem is that for 99 percent and change of today's workers, their work is so far removed from passion that if they weren't getting paid they wouldn't do it. Would you go perform your vocational role tomorrow if it were entirely decoupled from salary? If yes, congratulations.
The counter-argument to this would be the notion that all the best players in their perspective roles are those who are exceptionally passionate about what they do, from Yo-Yo Ma to Warren Buffett and Oprah Winfrey. Ignoring for the moment that Oprah "stood on the backs of little people!" to get where she is (thanks, Bill Burr!), I think saying that because they're passionate they're excellent performers could be putting the cart ahead of the horse a little bit.
Malcolm Gladwell is well known for his exegetic Outliers, which debunks the myth that performance is something with which a person is simply born. Terrifyingly and gratefully he puts the onus of excellence on the shoulders of the seeker and in so doing eliminates that particular "out" that people tend to cling to—by being absent of a particular talent, many then feel absolved of any responsibility to themselves or others to do what they can with what they've got. It's avoidance of the self-assessment that Ericsson says is so crucial.
The journey to truly superior performance is neither for the faint of heart nor for the impatient. The development of genuine expertise requires struggle, sacrifice, and honest, often painful self-assessment. There are no shortcuts. — K. Anders Ericsson
Coming back to the cart and the horse, I think it's more likely that people at the tops of their professions—here Elon Musk or even Mark Cuban would be good examples—are passionate about what they do as almost a side-effect of their expertise, rather than the other way around. Instead of being passionate about a particular topic and therefore becoming excellent at it, it seems more likely that they developed proficiency and then passion followed. Indeed, Mr. Musk has said that his drive to perform is "disconnected from hope, enthusiasm, or anything else. … You just keep going, and get it done." Here you have likely the world's best applied engineer saying that he divorces his performance from his passion, which discipline is worthy of its own discussion at a future date. So I think it's more a question of getting really, really good at what you do (the best, if humanly possible), and then anticipating that that will translate into future passion.
The hanging-chad question for me is whether one becomes passionate about their specialty, or whether having a game-changing specialty simply lets you exercise it in a flexible direction. I'm teaching myself the programming language Python right now; were I to become the world's best Python...er through my 10,000 hours of dedication and devotion, does that mean that I'd become passionate about Python itself, or that I'd be able to simply leverage that skill into a place of interest? My gut says a mix of both, but that's open.
Either way, it's clear to me that the best path forward is one of patience, sacrifice and "honest, often painful self-assessment." I want what Mr. Martin said, to be so good that I can't be ignored. I'm working on it. It's slow. It's zig-zaggy. But it's fulfilling to look back and see progress.