Unless the people you know are still using the iPhone 1 from 2007, I doubt the battery is worn out enough to warrant changing it. Google and Apple stop supporting their phones 5 years after release, which you should be looking into an upgrade anyway.
That may be true for people who waste a lot of money being on the cutting edge of everything, but most people I know use very old phones.
I stick with my phone until it cannot hold a charge anymore.
I get why replaceable batteries are a good thing, but you don't need to get the latest one every single time one comes out.
Unless the people you know are still using the iPhone 1 from 2007, I doubt the battery is worn out enough to warrant changing it. Google and Apple stop supporting their phones 5 years after release, which you should be looking into an upgrade anyway.