I live in the EU and here people don’t often upgrade phones. This might be a US thing.
If I were to guess it’s the average user who upgrades all the time because the carrier offers it and after 2 years they are bored with the phone. Some also think that tech gets old and must be updated often.
Tech enthusiasts know it’s not true but the average user has no idea. Plus there are iPhone users who just want the status of having the latest phone.