I think you're off a bit. LOTS of people buy flagships and hold on to them for longer. My wife and I buy iPhone Pros and keep them for 4 years or more. I only switched this year because I saw a deal and wanted to replace it BEFORE a problem arose. I like being able to throw away lightning cables and wanted the nicer camera, but TBH, neither matters to me (I charge wirelessly). I can't tell the difference in performance nor image quality and the battery life was always perfect on my last phone, even after 4 years. I've noticed a very similar pattern among peers and coworkers.
Modern phones are of higher quality and there's no new features to make us buy them, so they've gone from gadgets to cars. Both introduce cool features so slowly that many just want to buy something nice that won't give them problems. Buying a new phone used to be exciting, but my iPhone 17 was the most boring purchase I've ever made. This is a good thing. My new phone is of very high quality and will likely last more than 5 years (I take very good care of my devices).
iPhone users in the USA tend to follow a few patterns:
1. Status seekers: I have a few coworkers who buy EVERYTHING announced at every apple event and eagerly show it off around the office. Even they're bored. Probably some will upgrade to the 17 because it looks different, but they didn't care much about the 16. They actually resemble your description.
2. Women: Where I live 95%+ of women who can afford to, run an iPhone. If they're poor, they have a cheap android or old/used iPhone, but none own fancy androids. Even then, they're almost always grandmas or harried moms. Women really fear those green bubbles.
3. Apple as Default Users: There are people who just don't give a fuck. They had to pick a phone and if you don't want to put any thought into it, Apple is the safe bet. They couldn't tell you all the features on their phone. They're they way I am with my car...it just gets the job done.
4. Rational users: These are people who put thought into it and made an informed choice. This is me. I loved Google phones...until they stopped innovating. So I chose an iPhone, mostly for reliability. I like the android OS better, but not enough to deal with hardware that may or may not be reliable. I actually fully embraced the ecosystem and use it heavily for work and personal productivity. 10 years ago, Android was the better platform, IMO...better hardware, better cameras, USB instead of 30 pin...then USB-C instead of lightning, better cloud services, etc. iPhones kinda sucked for awhile while Androids were rapidly advancing. Now Apple services still are inferior, but they're "good enough"...same with their apps...inferior to Google, but they're cohesive and adequate. Their hardware is better and everything is extremely reliable. Apple is consistently and methodically improving...Google? they're like seem to have the attention span of a puppy with severe ADHD...and they seem to have lost all interest in Android...really anything not-AI: Google Nest, Google Fiber, Google Apps...used to be AMAZING...but now they seem to get no love or attention.
However, now Apple is basically Lexus and Toyota and Android is the US car makers....and I drive Toyota because I just don't care...I want something reliable that works so I don't have to think about it.