Where's the speculation? I shared a concrete example. Places without that method of funding have more equitable education systems.

I'm not really concerned what others are saying. You made the claim that "There's no reason for my health to be harmed just because someone has more than me." I just gave an intuitive explanation of how this could happen. And you can see this happening on a global scale: wealthy countries attract more higher-skilled workers, like doctors. These are educated, capable people not contributing those skills to their home countries (to be clear, I wholeheartedly support open immigration policies, but that doesn't mean "brain drain" isn't real).

EDIT: ah, I was not reading carefully, and realize you are saying "I see no reason for my health to be harmed by the sole fact of being poorer than someone else." I am not familiar with Sapolsky's research and can't speculate. In principle, I do see why you'd think it's hard to disentangle the material impacts of inequality from the psychological.