Conjecture

The argument that settles it is not a statistic, it is the shape of the gradient. Health tracks socioeconomic status at every rung of the ladder: the rich are significantly healthier than the poor, and the super rich are healthier than the merely rich, and the slightly richer middle class are healthier than the slightly worse off middle class. Material deprivation cannot explain the top half of that curve, because the merely rich lack nothing material. A gradient that continues above the point where needs are met is evidence that position itself is doing the work, which is why the mechanism has to be psychosocial rather than nutritional.

Risk landscape