As far as I recall, the studies on happiness were all cash flow, not wealth. It takes quite a bit of wealth to get to the cash flow limit that /may/ stop making you happy (60-80k/yr iirc). Unless you think ~50% of your waking hours are worthless and can be given away for free, you need that wealth before these limits become a factor (even if one's job was perfectly aligned with their life meaning, which isn't the case for almost anyone, they could just do it anyway with the wealth, minus the economic insecurity; otherwise (i.e. for almost everyone) they could do something either more fun, or more meaningful, or both, with the time).