We're all parents with school-age kids and my impression is that most people around us are just constantly striving for more or the next thing or this but better. E.g. schools - not just any school but the right school, similar with houses, but also things like cars, clothes, hobbies.
I concluded after many years in the UK, having a child there, that it came from a culturally-specific form of social anxiety, prevalent among the middle and lower-middle classes. It's a terror of being 'left behind', a fear of not 'getting on' relative to other people. It comes from a lack of confidence.
(Hang out with more foreigners would be my ultimate advice.)
I actually found it way more tiresomely prevalent outside of London when we moved away -- lots of the people we knew in London were living with kids in tiny Soho flats because they liked it, or creatives living on air as property guardians, or had interesting jobs as literary agents or opera directors that didn't make them much money, or where incomes fluctuated. (Obviously, even living frugally in central London is expensive, but these people chose that over private schools or flash cars.)
Living in a midlands village was the first time I'd lived somewhere in England where I saw bafflement and suspicion that the income we were clearly presumed to have from our jobs (and in fact did have) didn't translate into the kind of house, clothes, car and possessions etc we 'should' have had. I mean, I only worked this out after a few years of living there -- I was initially just surprised that people I barely knew were so eager to come to our house, or seemed to struggle with us not putting DS into a private school, or that we didn't ski.
Now I no longer live in the UK. I live in a traditionally-prestigious city neighbourhood dominated by often extremely expensive but generally rather battered Regency and Victorian houses, inhabited by senior medics and architects and academics (because it's near hospitals and the university) but also by Deliveroo delivery people and student rentals, all of whom cycle or walk everywhere (the steep terrain means many houses have no off-street parking, so a lot of people don't have cars), and virtually all of whom send their children to the nearest school, where DS goes. Unless they're actually wearing a Deliveroo backpack, you can't tell by looking whether the person cycling past in a helmet and hi-vis is a cardiothoracic consultant or a music student. Don't get me wrong -- there's a huge amount of social and cultural capital washing around here, but it's not generally being expressed by choice of possessions, clothes, children's education, holidays etc.
Social competitiveness is a choice, and a fucking tiresome one. Opt out.