I don't really see a lot of elitism in these circles - there's a chunk of such engineers that did not in fact go to Exeter and Harvard - but what they have in common is they are all to a fault very bright technical people that can produce complicated things quite quickly, and can communicate effectively with people around them - to make sure that what they produce is in fact useful :)
I genuinely don't think people that went to Exeter and Harvard (or MIT or Stanford or Penn or other JS feeder schools) see the rest of us as human unless there's another common factor like being employed by Jane Street and having those quirky hobbies the rest of them do - and then they rationalize it away by saying that the exceptions didn't apply to top schools, or were admitted but didn't attend for "financial reasons".
I interact with those people regularly without having the same background as them and this has basically never been the case. I think you've just been talking to horrible people.
You can levy plenty of criticism at finance. But they certainly take smart kids from wherever they can get them (for certain jobs; for others you need certain polish).
Personally know of 1 from Ghana and 1 from Nigeria - both engineers in HFT - both emigrated to the US post-college - so not that rare. Is it proportional to population? Of course not. Clearly there's going to be an english-speaking bias and an education availability bias and whatever bias du jour one wants to bake in. I don't think it is controversial to say that being born into poverty hurts - as naively as just accounting for malnutrition, for example, and going from there...
idk to me bottom 20% is a household thing more so than geographic if you live in Ghana or Nigeria but grew up driving a Maybach or BMW that would't apply if you grew up homeless in the US it would
perhaps ancedotal but the bottom 20% more or less stay the same across generations no matter how welcoming an organization is or no matter if an individual is bright or
has a good idea
