I'd imagine that the people they studied in Bangladesh in that article are a lot more poor than basically anyone in the US, especially people with $3k to spare

I'd imagine that the people they studied in Bangladesh in that article are a lot more poor than basically anyone in the US, especially people with $3k to spare on anything. And if you were to find evidence of poorer people having impaired decision-making skills in the US (and there might be evidence of that), the question becomes, are they as poor as they are because of that poor decision making?