A good indicator that someone is simply being dogmatic and not arguing in good faith (e.g. actually trying to understand someone's POV, and being open to being proven wrong in their assumptions) is when it takes them 5-20 minutes to reply until a particularly good point is made and then they disappear into the ether.

That's called "having a life" or "living in a different timezone"

When did upper middle class start meaning upper class? Something like 90% of Americans identify as middle class now.

That's why someone's self-described position means nothing. Something like 80-85% of drivers describe themselves as "above average" at driving, too.

The upper limit and the median of the household income quintiles as of 2022 are:[0]

  Lowest: $ 30,000 / $ 16,120
  Second: $ 58,020 / $ 43,850
  Middle: $ 94,000 / $ 74,730
  Fourth: $153,000 / $119,900
     Top:        - / $277,300

I think getting into the weeds on whether $80k or $100k or $120k/yr is a middle class sort of misses the point, but at least with my eyes it is hard to argue you're middle class if you're making more than about $150k at the most.

Even the GP, which I directionally agree with, says "upper-middle class is people making ~$200k/yr" but you're deep into the top quintile by that point, probably top 10%. I don't know what percentile I consider "upper middle" but it's definitely lower than top 10%.

[0] https://taxpolicycenter.org/statistics/household-income-quin...