That's not true. The returns in happiness are just logarithmic with respect to income (diminishing returns but still positive at each level). The story about no benefit beyond a certain threshold was generated by journalists misreading the plots in those studies.
I'm "rich" in the sense that I have a good job and don't have more responsibilities in life than I can afford/handle.
I make good money which means my employer thinks highly of me and invests in me. And this means that because there's money behind all this, they can afford to send me on business trips which are inherently more interesting (a few times a year) than sitting at my desk during that same time. And because I don't have more responsibilities than I can handle, I can just bail on my home life for a week or two to be away. And because I'm not on a shoestring budget, I can afford to do interesting things while I'm away on business.
I can't help but think if I was working at a subsistence level, I wouldn't be able to afford to leave my wife behind for a few weeks, my employer wouldn't be paying me to do work that could even require travel, and the trips would be out of the question because they'd represent a relatively large % of my compensation. And even if I went, I wouldn't be able to afford to do anything fun, so I'd dread it.
Just like when I've worked for poorer companies doing the same job.. sure, the work is roughly the same, but they can't afford to invest in hardware as much, so we don't get to do things "right".
I know it's somewhat tangential but I just feel like the very fact of having a higher-paying job opens up all kinds of opportunities that aren't necessarily so easily represented.
Research has shown that past the subsistence level, increases in income don't correlate with increased happiness.