One can apply a brief sanity check via reductio ad absurdum: it is less logical to assume that poor individuals possess greater intelligence than wealthy individuals.
Increased levels of stress, reduced consumption of healthcare, fewer education opportunities, higher likelihood of being subjected to trauma, and so forth paint a picture of correlation between wealth and cognitive functionality.
Increased levels of stress, reduced consumption of healthcare, fewer education opportunities, higher likelihood of being subjected to trauma, and so forth paint a picture of correlation between wealth and cognitive functionality.