I mainly bought the 3D printer for creative reasons, like support for other hobbies: stands for lego pieces, train modelling and other kind of dioramas (e.g. Hot Wheels), board games, tabletop and minis, storage… and of course static dust collectors (decoration) 
I’ve also used for simple repairments, I’ve always thought this opens up a lot of possibilities
When free time allow, I want to learn to use 3D design software, that’s where I think it’s the full potential of the 3D printer
What I completelly discard is selling, the level of commitment required is out of reach for me and would lost the enjoyntment of a hobby… but I may convince my wife to do that 