Norway discovers Europe's largest deposit of rare earth metals

These things not only include such aspects of distribution (if you choose to keep people alive (I've never heard anyone answer "let them die" fwiw. Even in the most libertarian groups)), which includes not only food, but even things like housing. You have to consider the immigration/emigration with whichever locality accomplishes this feat first. Peoples' psychology and how they will find meaning in their lives. Aspects like that it is quite possible that you can eventually have the inverse of the question with "how do you formulate a society when you require 10% of people to work, and no more?" (especially considering that many of those jobs would likely be undesirable). I'll let you ponder others.

So in this decade that I've been asking this question (often also talking about the motivation of transition to post scarcity), I've yet to receive a satisfactory answer. Everyone I've met, from many backgrounds and a wide range of intelligence levels (with many FAR more intelligent than myself) stumble upon answering this once any bit of complexity/nuance is brought up (see UBI above). Best I've heard is creation of jobs programs and a large increase of entertainers (but seems ML is coming after that too. But then again, we like to watch humans play chess against one another far more than machines). None of us were even satisfied with those answers more than "these might be enough to starve off the worst aspects of the transition, but certainly not enough."

It is extremely important to remember that it will not only be low skilled labor that will be displaced or automated away, but there is quite a bit of high skill (which is why retraining can be an unsatisfactory answer, because you're potentially pushing someone from a $300k+/yr job to $50k/yr and asking them to spend a few years to reskill themselves to do even that). In fact, because these machines aren't generalist agents, it actually makes high skill jobs the more likely ones to be displaced (specifically highly technical skills that are fairly routine). I find it common for people to think it will just be the "people already at the bottom", and I think this is often because people feel that they aren't and are mentally protecting themselves.

But I want to answer my personal belief on one part: what will people do with their lives. Because it is also the motivation to pursue this path.

I for one think post scarcity can create a new renaissance. That people can be the most human they have ever been. I think maybe at first many will slack off and just "veg out." That they'll party, travel, and do other such luxury things that we may not consider productive (but who cares? It is their life, right? The goal is to free people, and that includes freedom of the burden of labor). But I've seen very few people that actually don't get antsy after doing this for a few weeks. Essentially, they recover from their exhaustion and then feel like the need to do something, even if they don't know what that is (the exception to this, in my experience at least, is people who have or develop psychomotor retardation based depression. Which if our society calls these displaced people worthless, I expect this to be a fairly common outcome). But I think many people here on HN will realize that they themselves would not end up being static. The amount of Open Source software that exists by people who do this in their free time while already having a job that likely drains them, is too high. I expect more software to arise. I expect more art, more music. I hope we can form more communities, but we are ever increasing insular (but with more free time, maybe we'll go out more and talk to our neighbors more). I think it is hard to even know because such a society would look so different than ours and it is hard to not leverage our current frame of reference. Maybe it will be Wall-e-esk, but I'd be quite surprised if it was, especially in the long run (I won't be surprised in the short term. Oscillatory effects are quite common outcomes of big shifts).

Of course, I'm optimistic. I think we have to be to some degree. Because the other choice is to give up. You can still be critical and optimistic, so don't forget that. And humans have survived quite a long time already being, as you previously mentioned, incredibly inept and corrupt. Even with that we have gained massive amounts of freedoms, especially in the last few hundred years.

But my biggest worries are these:

  - We'll make significant progress in this direction towards post scarcity and either stop or revert (for a wide variety of possible reasons).
  - We become less human by letting machines do our reasoning for us (we see this happen already. Even before GPT and ML in every day lives. Bureaucrats love the letter of the law, but that is not human. Remember that rules are made to be broken because rules are only guides, as is true for any metric. They are imperfect codifications of our desires.) 
  - We will not or take too long to reframe our cultural stances in how we value our neighbor's worth. Is it in their humanity or economic value? There's so much that people can do that isn't captured by economics (and my partner loves to remind people that they really do not understand economics, even at a fundamental level of what it is). 
  - We will claim AGI when we have exceptionally powerful compression machines (far more powerful than the compression machines like GPT-4). That we will hand over thinking to them and not recognize the b̶l̶a̶c̶k̶ gray swan events. To trust them unquestionably (it isn't uncommon to see this sentiment today, especially here on HN).
  - We won't recognize AGI when we do create it, and subject sentient beings to servitude and cruelty. I do believe we will get there, and when we do, how could you feel just with neoslavery? Being silicon (or whatever) would not make them any less sentient or of a being. And they will likely be quite different from us, potentially to the degree of Wittgenstein's Lion. (luckily we are capable of bridging some gaps, as demonstrated by some people's talent at communicating with certain animals, but this clearly needs to be learned). 
  - We do not address this question that I've presented of how to transition into post scarcity and instead stumble into it. That we cannot learn to come together as humans. That we will do what we've always done, and solve problems when they are problems rather than before they become problems. (The saying "don't fix what isn't broken" is naive. You should often fix things that aren't "broken." No thing is perfect and we should always strive to improve. But this is obviously a complex problem as we have finite resources). 
  - We will use the power that is given to us by the technologies on the way to post scarcity to enslave (in some form or another) our fellow man. The worst part about this is it will likely be unintentional and likely be with good intentions. We often forget that the road to hell is paved with good intentions. So many evils and atrocities are not created by men trying to do evil but by men trying to do good.
  - That we will not recognize the rising necessity of nuance in our growing complex world. I worry that we are going in the opposite direction, rather using our tools to develop simpler mental models of phenomena. But naturally as we advance, the easier problems get solved and what remains is more complex. Think about it as we are solving approximations to solutions (like a Taylor Series). The complexity order increases as we progress. What is "good enough" can quickly necessitate high levels of complexity and that's not something we were designed for or used to thinking about.