I think a big issue here is that you're operating under the assumption that humanity as a whole is incredibly selfish, uncaring, and unable to operate cooperatively without a centralized force that is able to adequately threaten people to cooperate against their natural instincts. If that is your base assumption, then you will have to conclude that Anarchism isn't viable because it doesn't have enough threats or sticks to keep people from reverting to some base-level of antagonism, laziness, or self interest.
Where on the other end, due to the evidence I've seen of how humans organized in egalitarian societies as the norm until around 8000 years ago (from compelling evidence put forward in David Graeber's and David Wengrow's The Dawn of Everything), as well as the success of the Anarchist Society in Catalonia during the Spanish Civil war, I believe that humans would demonstrate their true nature is cooperation and egalitarianism if finally provided a society that does not actively incentivize our worst traits like our current one does.
We work ourselves like dogs and normalize it because previous standards aren’t good enough. What was idyllic in 90 AD is torture in 1990 AD. And this is good! It encourages society to ever move onward, to not be satisfied with what it has.
Most people in the US are barely able to afford basic food, housing, and transportation. They are working harder now than they did in the 1970's without any meaningful wage growth since that period, despite their actual productive capacity increasing tremendously since that time.
You really think most would choose to continue struggling with bills, or to be two paychecks away from homelessness vs. a society where all of your basic material concerns are guaranteed as a human right?
And you realize those people can choose to do whatever they want with the those 9 months of free time? They can still choose to become doctors, or engineers, or scientists, or to create the things that give meaning to their lives? They just won't have the threat of homelessness weighing above their heads if they don't instead choose to work for someone else to make them richer.
We are creatures with very limited lifespans, and every hour becomes precious when considered.
All the more reason to question the utility of capitalism, if only a minority are able to achieve the fruits of all the time spent doing things we'd rather not be doing, if every hour is so to be considered.
… but the reason why people are overworked is not because society ‘gives’ us too little to not work ourselves to death; it’s because people value things other than free time.
If you truly believe that, then our entire worldviews are completely incompatible. I don't mean this as an insult, but from my perspective your judgements on why people work so hard are quite detached from reality.