I can imagine money having diminishing returns on happiness, so there's a line beyond which money stops correlating strongly with happiness. Though I've read that if we redistribute equally our global wealth, we would be waaay below that hypothetical line, hence, for now, we should still be growing the pie, at least if we believe in equality.

But I think I see your point now, for the people currently beyond that line, subjective views of the world dominates their desires, so the axis where we want progress are now more diverse among individuals, and progress in one axis tend to harm progress on other axis, hence why there's more conflict

Money helps with reducing misery. But it helps little to improve happiness. When you can afford warm, dry and comfy shoes, that will take you out of damp misery. But comfy feet won't make you happy day in, day out.

People have subjective views of how they define progress too. For me, splitting the pie equally sounds like retrograde soviet nostalgia. I don't believe equally sharing the pie makes the world any better. Productive people (actually productive) should get bigger piece of the pie than slackers. On top of that, functioning market is important to find ideas that work. Otherwise it's straight to failure of central planning.

I agree with everything you said there

So I think our difference relies in how much our happiness is tied to relating to others

And I'm not sure how we can answer that. But I do feel my happiness rarely relies on relating to others, instead it relies more in socializing (laughing out loud or playing games with friends), and by making progress towards my moralistic goals, mostly with the point of view centered at society, our species, or all life beings