"they still do" is just begging the question. Plenty of people live without working. We're ruled by people who don't work.
If you tested the claim it wouldn’t tell you about human nature, because it’s possible (and I think likely) that most people are simply conditioned to believe they need purposeful work to be fulfilled, so you could just as well argue that if society were to be radically re-engineered, it would be worthwhile to re-engineer it at the psychological level (such that no one felt the need to work), rather than the economic level (such that work was made available to everyone).
> We're ruled by people who don't work.
I don’t have any data to support this but I suspect the majority of those people that we would characterize as happy are still engaged in an occupation (not a “job” as such, but purposeful work that goes beyond mere leisure). I’ve seen dozens of well-to-do retired boomers who waste away on Twitter or YouTube and don’t seem to do much of anything anymore, which is what I’m guessing is the behavior you’re imagining when you talk about oligarchs not working, but I don’t see much evidence that the oligarchs are like that; most that I can think of have made no indication that they will ever retire. Now, granted, work looks a lot different if you’re Warren Buffett, but what we’re looking at is not the social benefit of work as such but the impact of structured, purposeful activity on an individual’s psychological sense of wellbeing. In that sense, I think it’s unlikely that these people would disprove the premise.
you can't claim an invention is invalid because there are no "studies" that show such an invention has already existed and succeeded, you'd by definition never invent anything!
Working is objectively good for your health. Stopping work is associated with an extremely large increase in mortality risk, for both healthy and unhealthy people.
Any alternatives must weigh the resulting death it will cause.
If I had a study that showed increased mortality in people who had owned a parrot for 50 years in the year after that parrot died, you wouldn't cite it as evidence of the basic human need for a parrot.