Given two people, one who had money and therefore lots of high-quality STEM education, and another who does not have money and struggling to acquire a STEM education while also dealing with poverty (and the poorer quality education that comes with it), yes, probably the rich kid will do better at their job sooner.
But there's nothing inherently preventing the poorer kid from doing just as good, if not better, a job. Get them on the job, help them deal with the obstacles, and they're just another person, and across populations that means equally likely to "perform" or "succeed." Meanwhile, you also have the advantage of their unique cultural perspectives.
You can have it both ways, the question is whether you take that information and say "fuck it, don't hire poors, they didn't get as good of an education and therefore will preform worse," or you say "if we invest time in this underrepresented culture, we may be exposed to markets we didn't even realize existed."