If you make a pipe, and it's really good, you sell it. That's how a pipe maker has things like food, and a house. That's all there is to it. There's no "Oh this one's really pretty, I think I'll just keep it and smoke it."
We make pipes to sell them.
One fairly well known pipe maker quipped to me once "Oh hell no, I can't afford to smoke my own pipes."
On top of that, there's this thing where you've beaten on a pipe for like, 8 hours. And you probably sort of love it but also sort of hate it, it isn't quite as good as you hoped but it's still your baby, right? So there's a mental aspect on top of any monetary aspect.
We all have rejects, we all have also-rans in terms of briar or a stem that didn't quite work, or a finish, or whatever. You smoke those pipes to make sure your airway is as good as you think, that the briar is as good as you think, that your button is as good as you think it is. There's very little pleasure in this. It's product testing.