As someone who studies STEM the only reason I can think of is money.

Yes, but also racism and elitism.

The smartest people from wealthy backgrounds can still absolutely despise the poor (there are people who are so ridiculously rich they can't imagine how difficult it is to struggle with poverty; sometimes they do a challenge to see if they can survive on low wages and find out the hard way that no, no they cannot); also you have people who hear about atrocities committed against the global South and are fine with it because they identify with some Western identity.

Sometimes these people can have a struggle with their conscience (apparently Churchill said something about feeling guilt at a young age about the wars in Africa he was involved and the things he was doing, but then got over it), which is where propaganda can patch over the holes.