I don't think I can honestly wear out any of my guns in my lifetime, assuming they were a quality brand and not abused/neglected.
Slightly OT, but related:
I am trying to think of ANY gun I've broken or observed actually damaged or breaking (outside of ammo related causes or user errors, which is different) I can think of only two.
1. While at the range, probably now 20+ years ago, a friend had a new polymer Smith and Wesson striker pistol (the SV9 or whatever series). The frame was defective and broke into many pieces while he was shooting. It just crumbled. The gun was obviously ruined. SW gave it a brand new one as a replacement.
2. About 5 years ago, I bought a Ruger Security Six made in the mid-1970s. So at that point the revolver was 4 decades old, and looked every bit of it. It was not a safe queen and clearly a used revolver, although not abused. While repeatedly working the trigger and hammer (not dry firing per se, just repeatedly cocking and releasing the hammer) the trigger spring broke.
For overwhelming number/% of guns, I think the things that go wrong are probably the little springs and guts. Or neglect, abuse, user error. I don't think I've ever seen a worn out barrel from shooting too much.