I want to start by thanking you for making this thread. It's not easy to put yourself out there, and you've already sparked some great discussion.
Now, I'm 21, US, have struggled with depression quite a bit, and have spent the last year and a half in a job I absolutely hate in order to pay for school (Just so you can get a sense of where my perspective comes from). Every second has been worth it.
See, whenever I get down about the whole "capitalism / money " issue, I always keep two things in mind:
1) Champagne in a penthouse is still drinking alone.
2) Everything will be OK, even if it's not OK, it will be OK.
The first one you seem to have a fantastic grasp on, even if you haven't quite internalized it enough to allow you to stop the envy and all else.
The second is something my mother used to say to me when I was a kid. What she meant by it is that we do, as you say, always find a new "neutral point", but that goes down as well as up. The human mind can get used to anything and everything.
How I deal with capitalism, and the world, is I mostly compartmentalize and ignore it. I've found friends, and it's taken me a while, but I've found friends who don't think in social capital. They'll be there for me when I need them, and I'll be there for them when they need me, but not because of any social capital. We'll be there for each other because we genuinely like and respect each other as human beings. Finding this takes some doing. I've burned a lot of bridges I maybe didn't need to on the way. But, it's all been worth it, because now I can call up friends halfway across the country and they'll pick up. I'd say surrounding yourself with good people is the single most important step to battling whatever darkness you face.
When it comes to money, I've found that I can get a job with enough to pay the bills. I'm left with a modest amount left over after that. I'll put a small bit of it aside to save up for whatever shiny toy I might want, and the rest of it I use to buy experiences. It's not a bad deal at all, if you do it that way. Most of my money goes out to bars, skydiving, pool, things I'll remember. Yeah, maybe it sucks that I have to pay for that things, but at some point you just accept that this is how the world works, and there's been some form of it around since we invented wealth.
Other than that, I've found hobbies. Hobbies I can sustain for free. My biggest one is writing. It costs me the price of notebooks and ink. And I can do it for hours. Finding something you enjoy, you truly love and have a passion for is an incredibly important part of both getting past living in a world ruled by little green pieces of paper, and my depression.
Finally, to address the jealousy, I find that at some point when you have the other things, you just let it go. After a certain point in time, your happiness is an internal action. Not an easy one, mind you, but an internal one nonetheless. When you've got friends, and experiences, and hobbies, you stop feeling the need to keep up with the Johnsons, because his car might be nice, but hey, I got to look at a cool car today, so I've got that. It comes down to spinning things positively, and accepting that what you have is more than enough. It's not easy to do, and there's no shortcut to it, I'm afraid, but it's worth it.
Sorry for the rambling route this took. Thanks for the post, deepflows, it's really made me think about some stuff.