First, I'd predict that much of the observed correlation between technical proficiency and wealth is just because both of them require some innate smarts. In general, I'm suspicious of claims that some field develops "transferable reasoning abilities", partly because people keep using that to rationalize their fiction-reading or game-playing or useless college degrees. I'm worried that math and physics and theoretical CS are just nerd-snipery / intellectual porn, and we're trying to justify spending time on them by pretending they're in line with our "higher" values (like improving the world), not only with our "lower" values (like intellectual enjoyment).
Second, if technical proficiency does build transferable reasoning ability, I'd expect the overall benefit to be small, much smaller than from, say, spending that time working on whatever contributes most to your goals (which will usually not be building technical proficiency, because the space of all actions is big). You should always be trying to take the optimal action, not a random "beneficial" action, or else you'll spend your time mowing lawns for $10/hour.
Edit: I think this comment is too hostile. Sorry. I do agree that learning technical skills is often worthwhile.
I'm worried that math and physics and theoretical CS are just nerd-snipery
No way, especially not physics. We as a civ need to do more of this stuff, not less, compared to what we are doing now.
I can't think of any category of human activity that did more to improving the world than the hard sciences. Maaaaybe some religions in the "convince people to stop killing each other and cooperate long enough to get science off the ground" sense.
Something that I've come to realize is that as a practical matter, intellectually gifted people who haven't developed very strong ability in a quantitative subject tend to be at a major disadvantage relative to those who have. The quantitative subjects that I have in mind as "quantitative subjects" are primarily math, physics, theoretical computer science and statistics, though others such as electrical engineering may qualify. [1]
This point is usually masked over by the fact that people who don't have very strong technical ability are often reasonable functional by the standards of mainstream society, and don't realize how far they're falling short of their genetic potential. They tend to have jobs that don't fully use their strengths, and experience cognitive dissonance around being aware on some level of far they are from utilizing their core competencies.
Consider the following:
I can't give a brief justification for this, but I have good reason to believe that the ~10000x+ differential in net worth comes in large part from the people having had unusually good opportunities to conducive to becoming very technically proficient, that resulted in them developing transferable reasoning abilities and having had an intellectually elite peer group to learn from.
I know a fair number of brilliant people who didn't have such advantages. The situation actually seems to me like one in which amongst intellectually gifted people, there's an "upperclass" of people who had opportunities to develop very strong technical ability and an "underclass" of people who who could have developed them under more favorable environmental circumstances, but haven't. Many intellectually gifted people who didn't have the chance to develop the abilities mistakenly believe that they lack the innate ability to do so. And people who did have the opportunities to develop them often look down on those who didn't, unaware of how much of their own relative success is due to having had environmental advantages earlier in their lives.
[1] James Miller points out that graduates of elite law schools may have analogous advantages – that's a population that I haven't had exposure to.