[patresh]

Some high paying jobs also come with high pressure and little free time which could harm life satisfaction. It could be that high earners that are likely to participate in such a study are the ones that have more free time to dedicate to spontaneous endeavors, therefore might already have a higher life satisfaction.

This bias can also exist for lower-paying jobs, however I would guess proportionally there might be more 80-hour/week type high responsibility jobs in the higher paying brackets.