Did you read my comment? I said they are in the second quartile, and they foot the bill for a lot of the ways that wealth improvement reaches people in the first quartile.
Although, across the part of the country where I am from, Appalachia, there actually are people in the bottom quartile, especially after you take addiction-related QALY metrics into account. I'd argue your knee-jerk "just cause they are inside America's borders means they don't have it comparably bad" attitude, which sounds like you're just regurgitating some Giving What We Can blog post or something, is more of the small view.
> You also see this as a zero-sum game: a process of extracting wealth from someone and handing it to someone else. Trade increases the overall amount of wealth.
You really did not read my comment. I said that we translate the whole distribution to the right (that is the part about making everyone materially better off) but by doing so we shuffle some people from the second quartile into the first quartile, or at least shuffle them to lowered status within the second quartile.
In terms of ordinal status, it is, by definition, a zero-sum game. If, no matter how much total wealth there is, the thing people care about is where they rank in wealth, then it is zero sum. You can't manufacture more ranks. And, the evidence (which you don't seem interested in) really does suggest that it is the rank that people care about (especially when you are ranked second-to-last), even if preserving your rank means denying yourself better overall conditions from a material point of view.
People might be willing to accept a lessened station in life if the offsetting overall increases in wealth that they get to see are significant in their lives. The fact that at least 50% of the population is more concerned with rank than with overall well-being is, for me, a shameful indictment of how little we actually use societal wealth to improve impoverished lives to any degree, let alone a degree that would justify setting aside primal Last Place Aversion.