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.
Yeah, that's not a good argument. That might be true for the very poor, sure, but not for the majority of the lower-to-middle of the middle class. There's fundamentally no difference between your average blue collar worker and a billionaire, except the billionaire almost certainly had rich parents and got lucky.
People really don't like the "they're not, they just got lucky" statement and will do a lot of things to rationalize it away lol.
The comparison was clearly between the rich and the poor. We can take the 99.99th wealth percentile, where billionaires reside, and contrast that to a narrow range on the opposite side of the spectrum. But, in my opinion, the argument would still hold even if it were the top 10% vs bottom 10% (or equivalent by normalised population).
