It sometimes amazes me that people switch their phones so often. I tend to have a phone for 3 years. Many of my friends change every year ! One step to towards reducing global warming is reducing consumption.
But you should also consider that those who switch don't throw their product in the garbage. The resale value of flagship phones, particularly Apple, is really solid.
For example, Apple today sells a 3 year old model (6s) for 65% of the price of its latest model. Even if you sell it second hand, you can usually get >30% on a 3y old Apple model. You can usually get like 75% on a 1 year old model.
I know a guy who buys a new phone every year and sells his old one. Say he buys every year the latest and greatest flagship for say $1000, sells it for around $750 a year later and buys a new phone. He consistently spends about $20 a month on the latest phone. It's not as crazy as you'd think, $20 a month for the very best tech in your pocket is pretty trivial to most people on HN. The numbers may be a bit different for everyone.
My cell phone company basically gives them for free in exchange for the 2 year contract, so after my 2 years are up, I'm definitely switching it for a newer model, or I'm leaving money on the table.
Many people are way more careless than I am, or heavier users, and definitely switch every year (or even less!).
Chinese phones make it much more feasible. OTOH, if you care about environment, these are no good - no user-swappable batteries for instance.
Even if I went to China and bought the phone there I'd still be behind, no way to get a data-only contract for less than phone+data.
I'm not happy about it, it's just the way things are, and the reason I'll be switching phones next year (just because I'm basically forced to by the carrier).
I would have upgraded it in the last year or two but I can't find a phone I really want, nearly everything produced these days is a much larger form factor.
Yet here I am, with my one plus 2 and cannot imagine changing it within the next 3 years as the improvements are negligieable for me at this point. The only thing I can consider switching to is either an iPhone or the Librem 5.