You can try complicate the explanations to account for this but the fact is that it shows that the 'obvious' reasons most people surmise are not so clear cut and need to be tested like any hypothesis. It's a hard problem to test and there are several other competing hypothesis. The best I can say for my own beliefs is that we need to have more studies that need to be done before I'm convinced of any of them.
I explain this here:
https://news.ycombinator.com/item?id=14353914
It's cheaper to not exercise.
Also exercise is not for weight loss, it's for exercise.
Also works for saving: earn more and spend less, duh!
Making friends: be nice more and mean less, duh!
Stress: sleep and relax more and worry less, duh!
Marriage: communicate and date more and fight less, duh!
Fat people want to be thinner. There are plenty of negative incentives to being fat. There's something subtler and more complex going on here.
Not too surprising that being immune or actively avoiding that toxic culture, results in both wealth and fitness.
Advertising Kills.