happiness = things_you_have - things_you_want
It's much easier to reduce your desires than it is to buy new stuff. Your resources are scarce and your desires infinite. If you can convince yourself you have everything you want already nothing can touch you. Write down a list of reasons to not buy the new hotness.
Stoicism has more to say on this, for example negative visualization. If you feel upset with your spouse or kids imagine them being hit by a car and dying in your arms. Car or truck? Did the car stop, or speed off? Burial or cremation? What will you say to your family, their friends? Manufacture details and explore their emotional impact. The frustration just evaporates.
We're happy as long as we're going vaguely where we know we should be able to, to get what gives us satisfaction
If you go for your quest in life, you may become very fulfilled and happy even when failing to obtain any end goals.
There are of course no guarantees or strict rules in life, so are just very general cause-and-effects in play.
The most obvious and probably biggest expense item (at least in the US) would be tertiary education, but having been out a few years I don’t really notice what the additional benefit was of top-tier private university vs cheap state university, since I know plenty of state schoolers making FAANG money and plenty of Ivy Leaguers struggling to find jobs.
Though at least for me the primary/secondary property race you describe was not an issue, since I went to school in NYC, which has district wide school choice for middle school and universal school choice for high school. (NYC is a million kids so the city is split into districts for ease of administration.) Elementary school was geographically defined, but I also went to a school with a C rating, and plenty of people from that school ended up fine.
That way, even if you were subject to feeling guilt over not providing the very best of everything, you can satisfy it this way.
"good enough" and "justified" must consciously and explicitly include some pie slice for "non-essentials" though. Some amount of "non-essentials" are in fact essential. Anything else is simply not living. So, once in a while, you do splurge on the expensive weekend.
There probably is a point where "best available" isn't worth it, but I think for many people, they still feel that they need to do whatever they can. NYC is a great example, where unless your kid makes it into Stuyvesant or Brooklyn Tech or equivalent, many higher income parents feel compelled to move to the suburbs. Or even the current uproar where they diminished the testing to get into those schools.
And so to maximize this probability, people stretch themselves to live in neighborhoods bidding against other people also stretching themselves to live in the "best" neighborhood they can afford.
I teach my kids that it might be a poor ROI to work for material stuff, but I do teach them the importance of wealth in being able to obtain resources in the future.
I have three.
If anything they have more options, they just have less concrete things.
Maybe those aren't true, maybe they're true up to a certain point, but in my experience, people will stretch their budget to put their kids in the better schools, and the rat race starts there. This might not be an issue if you're already a dual professional household earning $200k+ or something where you're deciding between $600k vs $1M houses, but more for whether or not a $80k income family should stretch and buy a $400k house or stick to a $300k house.
(numbers aren't accurate, just trying to show that there exists a tier of society that does have to make those tough choices between living comfortably within their means and offering their kids a meaningfully higher probability of future advancement).
I used to meet people in the NYC area who commuted 1+ hour each way everyday to work 8AM to 6PM at least, they were all doing it so their kids go to the best school district they could afford. I felt sad for them since it basically meant very little time with the kids during the weekdays, no gym, no visiting friends/family, cooking, but they all did it.
Let me quote you one of my favorite posts: "You say 'I can't do XYZ because I have kids and a mortgage?' - well maybe you should have thought about the long term ramifications of your actions."
Kids are just the same - except the other way around!
So personally, when I'm old and retired, I plan to depend on the work your kids (and the kids of other people who also generously considered the "continued survival of the human race") while in the meantime maximizing the benefits that come from the freedom of not having kids.
You may not like this freeloader spirit, and governments generally encourage people to have kids by various means ("working economy, GDP growth and all that are important after all!).
But as it's not illegal to "abstain" from the rat race, I do not care much :)
The Fight Club line has always really resonated with me:
"We work jobs we hate to buy shit we don't need"
Live below your means. Tune out from all the consumerism. Suddenly you find that you have enough savings built up that you could support yourself for multiple years without working. Now you are no longer willing to put up with as much at work. Oddly, this builds a sort of respect from people and they bother you less. Now you have excellent work life balance and more than you could ever want.
And really the key to it all is just not wanting so much.
(Also try to keep the freak-accident / illness destroying your life type stuff out your mind.)