JWs percentage of Whites (the group with the highest Income), excluding Hispanics, is less than 50%. JWs are more racially diverse than any other. So let's think. If America were to be as diverse as JWS are, would JWs still rank as 'noticeably poor'? So given the JW demographics, they do pretty good.
Hasn't it pretty much been discussed JWs are mostly middle class?
And Elsewhere, that survey is based on less than 300 people who claimed to be Witnesses in all 50 States. Think about it. That averages less than 6 people per State. Not so much of a great study, eh?