Humans are socialized to want purpose and meaning in life. Modern humans are socialized to put a lot of that meaning into their employment. Many humans have a lot of trouble with unemployment and even retirement, because they feel a lack of purpose.

I think imagining a world where people are universally able to find purpose outside their employment counts as "changing the definition of people". Perhaps less difficult of a change than making us not dependent on oxygen, but still a big enough change not to clear the bar.

> Plenty of people live without working.

A minority of people live without working. And many people who do not work are profoundly unhappy with that state of affairs.

> We're ruled by people who don't work.

That's a cute thing to say, but isn't a serious rebuttal of anything.

You’re right that my reasoning was off. I don’t think it helps the point OP was trying to make. The argument being made in favor of labor isn’t “The only way for someone to be happy is to have a job” but instead “The majority of people will be unhappy without an occupation,” which is testable. The existence of people who are happy without any sort of structured, purposeful activity would not invalidate that the majority of people may well need structured, purposeful activity in order to feel fulfilled.

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.