Also, I dispute that buying lots of junk is unnecessary for a decent life in industrialized societies. We are socially competitive animals and if someone were to just focus on "survival", he would end up being a social outcast pretty soon and his mating prospects would have shrunk considerably. Being lazy and having low-income is a pejorative description in industrialized tribes. But Western society has such huge income gaps that no matter where you are in the income spectrum, it looks like there are thousands of people above you living the good life, right up until Bill Gates.
In contrast, in a hunter-gatherer society, the most accomplished guy might be the chief and the competitive pressure on each tribal is much lower. Hence, the possibility of a 20 hour work week.
TLDR, I dispute that technological advances will reduce work. As long as there are huge income gaps, we will have people relentlessly working long hours every day to obtain a better position in society. It is an instinct built into our genes.
Hunter-gatherer types don't have a home. If you are willing to go homeless, you can live for $15-20/day in most cities. That's less than 20-30 hours of work/week in most places.
Hunter-gatherer bands also have a total mating pool measured in the half dozens. If you restrict yourself to fellow homeless people, you're likely to meet a similar number of women, all of whom have roughly the same social standing. The problem is not that there are no mates available, it's that there are no mates that you want available.
Your point that people tend to measure themselves relative to people around them is true but orthogonal. If you hold living standards constant, you can achieve them with a lot less work today than you could at hunter-gatherer tech levels. It's only because living standards are not constant that people have a tough time earning a living.
Being a hunter-gatherer born in a stable hunter-gatherer society is not at all the same as being a homeless person in the industrialized world. For the most part hunter-gatherers in a hunter-gatherer society aren't ostracized or looked down on by everyone they know, criminalized/shamed for living (finding "acceptable" opportunities to sleep, eat, piss, etc, are much more difficult for a homeless person), or surrounded by messages that a person's worth is measured by whether they own the right things. Being able to comfortably meet biological needs, having meaningful social connections, retaining dignity and self-respect -- these things mean a lot.'N!ai, the Story of a !Kung Woman' is an interesting documentary about a woman whose life took a dramatic turn for the worse after the introduction of western culture, even though she probably ended up being the richest person in her tribe.
AFAICT more technology has nearly always led to us taking up different kinds of work to fill up that time, not more leisure. When modern household appliances were introduced, the result was higher standards for housekeeping. Women in the 70's spent slightly more time doing housework than women in the 20's did despite all the new "conveniences". Were houses in the 20's disgustingly filthy? No. Did the increase in cleanliness make society as a whole happier or better off? I doubt it. If anything, I suspect the obsession with cleanliness has just contributed to increased rates in allergies, weaker immune systems, etc. Technically, access to these appliances are considered a standard of living increase, but all it really did was make us pickier about what an "acceptable" living is. Now people who can't afford those conveniences have to work harder to keep up or be shamed by others for having a "dirty" house.
People comparing themselves to others is very relevant, because those comparisons have a huge impact on happiness and quality of life, and it is generally assumed that a higher standard of living correlates with those things. (If you disagree, can you explain why having a higher standard of living is a good thing? Why is it rising? Why do we even care about it?) If that's a wrong assumption it needs to be challenged because from what I can tell it's basically a cornerstone of western civilization right now.
Given that you're fucked over by your genes and can't actually make yourself happier, why not live your life based on maximizing your standard of living? At least that way, you can look back and say "Well, even if all those things I'm stressing out about happened, I lost my job and my family and had to go homeless, and no girls would talk to me, I'd still be better off than a hunter-gatherer."
It's not that achieving a higher standard of living makes you happier, it's that achieving a higher standard of living and believing that standard of living is the key to happiness lets you look back and see by an "objective" measure that you're doing better than you were before, and that makes you happy.
Genetics may be one factor, but relative differences in wealth is another huge factor that I know has been observed extensively outside of dominant western culture. In HG societies, there are almost no differences in wealth. Everyone considers themselves pretty well-off because there are very few things (or experiences) in their world that they could want but not have.
And even by the objective standard, a HG is better off than someone in the industrial world who has no job, family, home, or love prospects. An average HG has meaningful work, a large and close family, a mate, and considers their entire territory to be their family's "home". It isn't a miserable or unfulfilling life at all. The only way you could come to the conclusion that you're still better off is if you held really stereotypical and inaccurate views of how HGs live. Which leads like things like groups of us deciding that we have a moral obligation to nose in on what few HG societies still exist and bestow the gifts of technology and capitalism on them, so that they can live in slums for the rest of their lives and the lives of most of their descendants. Which doesn't exactly make them happy, because they go from being the richest people in their society to the very bottom of the ladder in ours.
I'm not going to live my life maximizing my standard of living because money and wealth aren't the same thing. Call it fulfillment instead of happiness if it makes you feel better, but having the biggest pile of money isn't the way to get there.