>Coming from an Eastern European country, my parents were making less than $10000 a year combined in the '80s and '90s. Nowhere near "wealthy" by western standards. However, they gifted me with a strong STEM education, which translated in material affluence 25 years later on a different continent.

That's the very definition of anecdotal evidence and survivorship bias. Both things that a strong STEM education should help squash.

It's also based on a historical peculiarity. In the west, and in particular in the US, to get a good STEM education you statistically have to be middle class or wealthy in the first place. (It's not impossible to have one if you're not -- just more difficult and rare). That wasn't the case in Eastern Europe, where the state provided easier access to higher education.