If you live by yourself long ago, how do you eat if you don't hunt/grow food?
Living by yourself wasn't necessarily an option. We're talking societies. And many are tighter, leaving much less room than ours to the idea of individualism (for the better and the worse, as tight networking can be as oppressive as solitude, and some activities requiring isolation -such as literature- can be misunderstood or frowned upon).
But, again, we must distinguish between "doing things" and "working", and the same activity can be labelled as either depending on context, mindset, motivations, representations, etc. "Working" is a culturally specific way to frame a task, and humans have shown alternatives.
We have peer capitalist societies that work less, why is capitalism itself the cause of people working too much?
You've seen in this thread how many meanings "capitalism" can have. European socialism, for instance, is a capitalist system - simply a regulated one. And in some contexts, capitalism means "the ideology of absolute de-regulation". Absolute de-regulation is very predatory, and this is what sets up abusive systems of dependencies and power differentials, modern forms of slavery, etc. But there's a lot of leeway within a capitalist framework, a lot of different ways to organize, a lot of possible values systems. One can be in favor of "capitalism" as a background basis yet against "capitalism" as an absolute de-regulation ideology. Unfortunately it's the same word with different meanings.
Some of what I said above applies. Advancing society requires more working that just living with your needs. If you want to enjoy fancier leisure activities (than just like socializing, dancing, very simple games, etc.) like say video games or bowling or what-have-you, those things need work for them to be available. I'm not too big on UBI because humans are gonna human (have to put in safe guards to protect us from ourselves), just like the main character from Office Space; if I had the option to do nothing, I would do nothing.
Our material society requires a lot of activity and a lot of production, that's indeed a cause of skepticism about universal basic income (how would all the activity slots be filled). But there's also two things to take in consideration :
First, there's the whole other can of worm of "growth", growth as a questioned implicit value. Our culture values it a lot, as a self-evident thing, and a false universal (other cultures don't, and they pay a price that we cannot anymore as few of us would give back our tech and material comfort). The thing is, it is being debated in itself, and degrowth movements are a thing. There are a lot of people considering it the only rational route. So it's thinkable.
Secondly, I do not trust you on doing nothing. i used to think the same about myself (often qualifying myself as lazy, and unashamedly so, as, sub-culturally, so were a lot of my fictional models), and I must confess that, given freedom, I've sometimes turned out the equivalent of workaholic : volunteering beyond schedules, for all the important things that had to be done, that had meaning, even when annoying to do. Actually much more than those who did it as a "job", with a salary and a "welp, look at the clock, am done" mentality. And I know that, in my field, volunteering burn-up is a thing (can you imagine that).
The (cultural) need for activity, for satisfaction, the sense of responsibility, a lot of factors drive people beyond contracts and salaries. It's a matter of personality and individual values, of course, but individual values are also the reflection of collective, cultural values. There are a lot of alternate conditions that motivate productive activities, and we tend to lose sight of them, by framing our world around coercitive work. Anyway, what I'm saying is : don't take as self-evident that you'd stay idle and unproductive. You or others. We tend to be surprising in that regard. And this image of idleness is also a product of our coercitive work as it's the other side of its coin (if you're "forced to work", you also feel forced to value and exploit the moments of allowed idleness).
Back to humans gonna human, the reason why we even need a concept like money is because humans will take more than they need (or fairly be entitled to). Even with money, we have a large percentage of people that live beyond their means as it is and rack up debt they really have no business racking up.
Money is yet another can of worms, and its reason to be is actually to manage debts. To pass them around easier. But you are wrong about "human nature". First of all, "taking more than entitled to" is largely cultural. You have cultures like ours that encourage this mindset, and others that shame it (actually, our culture does both, it's complicated and awkward). Cultural values get internalized, through education, socialization, mythologies, etc. And then they are applied. You could say that "second natures" weight much more than "natures". Whether greed-is-good or greed-is-bad, and how deeply these conflicting viewpoints get internalized, is largely a matter of the environment. What it presents as cool, ridicule or shameful. What feedback it gives to that. When you glorify material wealth and yet chastise greed, of course, it gets hard to avoid complicated double binds. Anyway.
[Another thing I forgot to stress out is : do not underestimate the power of debt, of its notion and feeling - it didn't and doesn't require money, and it's a very strong psychological pressure, for better or worse, even when you try to free yourself or to free others of that sentiment.]
Cultures always define "humans" (human nature) around their own values, always present their values (and their type of organization) as natural, universal and true - as opposed to the fake, counter-natural, absurd systems of other cultures. But their very diversity relativizes it all. The diminishing of this diversity (through global cultural conquests) is a sad thing, because we lose illustrations of mankind's actual range of possibilities. And so, we reduce our freedom, we believe more and more strongly in essentialist there-is-no-alternatives. Deconstruction is precious.
But yeah, it's also all very theoretical. As organisations tend to emerge rather than being thought out in advance and applied, there's a lot of unpredictability in that. Also a lot of inertia, you cannot suddenly decide for different structures, values, organizations, representations - it simply doesn't work (the French Revolution killed a king's kingdom to give birth to an emperor's empire, and you also see all the wonky hybrids stemming from colonization efforts). And I honestly believe that, while structural and cultural changes are urgently needed, we simply as a whole don't possess the ability to redefine ourselves fast enough. I think we're doomed, in practice.
But still, at the theoretical level, I think we must keep in mind how vastly diverse the possibilities are (were?), and how many of our constraints are (were?) imaginary. Human possibilities are richer than we realize when we're too much immersed in one culture and its image of itself.
