The 3D printers aren't too expensive these days. And there's TONs of practical stuff I've printed on it.
The danger with the 3D printer though is getting into the habit of buying too much filament. I do keep myself in check about that. The way I convince myself is that you have to keep the filament "dry" and so I have this large sealed plastic container that can't hold anymore filament.
I have 4 colors and the black in 3 different materials.
I bought the printer for myself and my wife naturally reacted with: "oh, nice... another toy!" But.... Now she agrees it has been a very useful "toy". I have printed useful things specifically for her and things that benefit her too, so that helped
I do not regret it at all. It has been a lot of fun!
Good luck with it! May be you can get some flowers to come with it, that may ease the acceptance at first...