One congregation I attended had more than the usual share of wealthy JWs.
They spouted the party line of "Armageddon soon", but they said it with almost a wink, while building up massive portfolios of investments and engaging in business dealings that secured a comfortable lifestyle in their "golden years".
In that congregation there were also some very (well, relatively) "poor ones". Not much of a middle class in that congregation. Those ones were almost proud of their complete lack of financial planning - "oh, we just rely on Jehovah".
That's been my experience - the handful of wealthy JWs act like anyone else in the "world" and invest prudently for the future, while the majority of the not-wealthy proudly view their lack of finances as a sort of proof of their faith.