You've cited some examples of people who, it is undeniable, are successful, but who also happen to fit your argument. But equally there are many successful businesspeople who did not study maths/CS/physics

If only there were some way of quantifying this.

Of course not by chance: there is a common cause -- high IQ.

Supposing his IQ to be at the 1 in 10k level (at the level of standard deviations, it's very unlikely that he's much higher than this, on priors). There are 400 such Americans of each age. What fraction do you think do publishable math or TCS research as college sophomores?

Bill Gates also famously dropped out of college. Does that warrant a Bayesian update, too? (Peter Thiel probably thinks so :-D)

Yeah, it's an update in the direction of it being a good idea for people of his demonstrated ability by that age and with his ambitions to drop out.

And I failed my first go at Machine Learning, and nearly failed my first go at Intro to Statistics!

(Because I hadn't taken continuous probability first, and was depressed.)

What was it like from the inside, hitting that wall? Math is a particularly easy subject to hit a wall in, because if you're lacking a prerequisite of some sort, all of a sudden everything you're seeing turns to apparent nonsense.

I also think it's weird that I see a lot of people throwing around 'good at math' and 'bad at math' as if those terms mean the same thing to everyone. Some people mean Calculus III, some people mean Fields Medal or thereabouts, and some people mean somewhere in between. Whether someone is good or bad will depend on what people mean.

Well, I certainly find it plausible that most reasonably intelligent (ie: at the mean to one standard deviation above) people can learn math to the level of, say, a first-year undergrad, or an advanced high-schooler. For one thing, some countries have more advanced and rigorous math curricula for high-schoolers than others ("engineering-major calculus" and linear algebra are reasonably common in high school curricula), and yet their class-failure rate, to my very limited knowledge, seems to vary with the quality of the pedagogy rather than being uniformly higher.

Could most people of such an intelligence level also learn an entire undergraduate math major? I don't know: nobody is trying that experiment. I do think most of the people who already complete engineering, natural science, or computer-science degrees could probably complete undergraduate math -- but nobody is trying the experiment of controlling the "double major" variable, either. Instead we discourage physics, engineering, and comp sci majors who don't voluntarily double-major from doing additional theoretical math courses in favor of the applied math they need for their own domain (ie: algebra for the quantum physicist, differential equations and optimization for the engineer, logic and computability for the computer scientist). And that's when they take a theoretical track, instead of just cutting out to the applications ASAP!

Could most people who do PhD-level research work in other natural and formal sciences do work in mathematics? At the research level, the distinction has collapsed: they partly already do! I've actually heard it said that you're not really well-prepared for PhD-level CS or physics if you didn't double-major in math, or for PhD-level biology if you didn't take an undergrad major or minor in statistics, anyway. You certainly can't work in type theory or machine learning (to bang on my own interests) these days without using and doing research-level work in "math" as an inherent part of your own research field.

It's very hard to make the relevant inferences when we lack data on what happens when we try to teach people math instead of using math as a weed-out subject, and then jumping out from behind a bush at young researchers in the other sciences yelling, "SHOULDA LEARNED MORE MATH!".

If you don't know how prevalent iron overload is, then you can't know that men tend to have it, so I suggest editing you comment to say "some men have iron overload" instead of "men tend to have iron overload."