I disagree with the premise you're basing the rest of your argument on. I would sooner say that a successful career in general (and engineering is no different) probably only hinges marginally on some intangible measure of aptitude (rephrased: aptitude is necessary but insufficient), and mostly results from some combination of coming from a privileged background (that is, encouraged from a young age that you're capable, exposed to good education, validation, having access to a professional network, etc.) and having had opportunity to thrive (for example, a lack of financial stress allowing one to pursue a risky business venture as opposed to having had to support one's family from a young age and therefore accepting a menial job straight out of high school).

Of course, one can find examples of people from underprivileged backgrounds succeeding in the sense you're referring to, but i don't for one second believe that simply "working hard" and "making the right choices" is enough to magically rise to the top of the economic dogpile. In essence, i think your statement is an instance of the just world fallacy (https://en.wikipedia.org/wiki/Just-world_hypothesis).

I've tried to be measured and objective in my reply, but i see this as a common myth that deserves to die, so my apologies if i'm sounding abrasive.