The reality is that life is amazing now even for the supposed "have nots" - providing they live in a first world country. Think about the spice trade - only rich people even had access to common pepper. Columbus discovered America... looking for spices! Now the poorest of the poor take their free money and can buy nearly every spice on the rack from anywhere in the world. Food Stamps provide the funds to eat extremely well, especially from a historical perspective. As I said, and you obviously understand, it's all about perspective. And our perspective is so horribly skewed that we think we have nothing when we really have it all.
I, like you, am more concerned with absolute standards of living than relative standards (I'd just like to see everyone have enough to live well, and would see substantial inequality as a good if it helped achieve that.) And I would certainly rather be (relatively) poor in the US now than poor in most other places, at most other times. Much of human history is a horror-show though, and I'm not sure we should use that horror-show as our only standard of comparison.
I think you underestimate the difference between living on very little by choice and having very little though. I can't say I live as if I were poor- I try to keep my spending to <25k a year, but will go to 30k if I really want to for some reason. That's actually more lower middle-class than poor for the US, but kind of poor where I live, and living here allows me to make what I make. But it's less than a third, edging toward a quarter, of what I take home, not counting some windfalls I get from time to time.
This gives me a tremendous buffer against what I consider the worst part of being poor- the insecurity of living paycheck to paycheck. If something goes really wrong for me I have years worth of money in the bank, and that can solve a lot of problems. When you live paycheck to paycheck, even if your paycheck is about what I spend, it takes just a little wave to swamp your boat. I know, because just a few years ago I was doing that, and I was like a long-tailed cat in a room full of rocking chairs the whole time. Luckily the worst thing that happened was that I had to borrow a little rent money, but if anything had gone really wrong I would have been in trouble. And I felt that the whole time.
I'm also in a position, now, to make the leap to something entrepreneurial as I please. And that's how you make real money. I have some side-hustle I'm hopeful about and if it becomes clear that it is a good bet I can take a year off unpaid to work on it. If it doesn't pan out I can just return to working and still have a healthy bank balance. I'm not, by the way, a mustachian who wants to stop working. I just want to work on what I want, when I want, as much as I want, with people I choose to work with. I just don't want to have to worry about how much I make doing that.
The thing about the US is that what you want is cheap, but what you need is expensive. I guess I'm biased, as I have worked to reduce my wants until what's left is mostly needs, but... the cost of flat-screen TVs seems unimportant to me (I don't have a TV.) The cost of housing in an area with economic opportunity seems the most important thing. And that's a big deal- I was in talks about a job with a company in Boston recently and realized I would need at least a 20k raise to break even on housing there (I do have cats, so that limits my options.) I would need a lot more for SF. Housing isn't exactly cheap where I live though- it's just not Boston or SF or NYC.
I'm all for personal responsibility and making do with what you have. But I'm also in favor of opportunity and, frankly, the rent is too damned high in the areas that offer opportunity on the US. I'm lucky in that I'm mid-career and have an unusual set of skills that works well remotely. I'm thinking pretty seriously about Mexico, because the rent is not too damned high in Gunajuato. But of course I can only consider moving there because I am not poor- you need to prove about 125k in cash assets to get a resident visa.