Why would they break more often? I don't really see that.

We have thousands of Xcovers (also replaceable) in the factories at work and they break no more often than the regular phones in the office environment. In fact people treat them pretty roughly because they're handling heavy requirement and you know how well people look after equipment they didn't pay for :) They're not perfect but they walk the walk.

Another point: I know several people that have Fairphones where almost every component can be user-replaced and I've held them but I don't see them being any more fragile than any other phone, really. And these are not rugged models.

And a Fairphone battery is 40€. An Xcover battery (including NFC antenna which is weirdly enough in the battery) costs similar. The screen 90€. All a lot cheaper than Apple, probably because there is no labor cost. You can just do it yourself or ask a friend who's handy.