To the OP (...unsolicited advice warning...
I would say your wife is resentful for some reason or another. She either doesnt have anything she is that interested in, or she feels that she cant spend any money on something SHE is interested in, and is resentful that you get to. (Whether the facts support her feelings is irrelevant at this point, you are dealing with emotion, not rationale....very important distinction...deal with feeling first, then reason later.)
It sounds childish, I know, but that is how some of us work, myself included. Of course it would be better to talk it all out and come to an arrangement or compromise so you can both have what you want. But when the wife is unhappy it usually has more to do with a need that is not being met than an actual dislike of your hobby. It is up to you to shed the light on what it means to you and does for you and why it IS worth it.
I know from my own exp that I really didn't understand my husband's need/desire to go riding around on his motorcycle all the time and while I dont stop him I am not really thrilled about it (mostly I worry) and I was really not supportive when he wanted to buy a new/used one since he had one that "worked just fine".
But that was before I had anything that I was allowed to spend money on. I had lots of interests, lots of crafts and art projects but I didn't feel justified in spending because we needed so many other things, or the kids needed things constantly. It was my job to make sure everything in the home ran smoothly and I had a hard time making room for myself. Any extra in the budget was spent on fixing up his truck or motorcycle, or four wheeler....etc. There was nothing left. That made me jealous. That made me angry sometimes too. And then I would get mad at myself for being selfish....a vicious cycle.
I would get mad when he would go riding and take it out on him when he got back. And then one day I realized WHY it made me mad and I had to talk to him about it.
He explained that this was something that he did for HIM. It was his personal time where he could just be free and not worry about anything. This was his release. It relaxed him and made him able to do the daily grind that keeps up living the life style we are accustomed to living. And in those terms I could understand it. Seriously it turned on the lightbulb for me. I never even thought about it that way before. Overnight he changed my mind about his motorcycle enthusiasm.
I no longer resent his time and I now go out of my way to make sure he has time to go ride whenever he can, especially if he is stressed. I will even suggest it to him. I even listen with REAL interest (not just pretend) when he talks about the engine and the machines he would love to have. It helped to know that he did not need an escape from me, just a break from the grind, the everyday stuff. God knows I could understand the need for a break with 3 kids at home.
The complete honesty has really paid off for me too, because last summer he built me a new living room (nearly doubled our living space in our home) in his spare time after his full time job, workin on it everyday... and he built in a special spot complete with plumbing and drain for my fish tank. It had been in storage for 5+years because this house was just too small.
He even kept his hands off except when I asked for help (acquiring gravel from the local riverbed) and has let me do it all. And is even supportive of my new efforts to plant the tank and doesnt complain about those upgrades. As long as I can explain it to him and he can see that I have done my research his is ok with it. He wont ooohh and ahhh over it, but he does like it. He is a man of few words but he is impressed with the amount of work I have put into it. And he loves that I didn't let him take over the project.
He tends to do that with me a lot....another of my frustrations and why I never had any major hobby. It also helps when I show him rtail price of something I want and then find it for a bargain somewhere else, then he sees that I am TRYING to save money.
A wife and mother WILL understand the need for ME time. The need to have a hobby that givs you a seperate identity than the guy who has to work all day, then be Dad and husband at home.
We all need forms of expression. And perhaps iIf you help her find hers then she will be a whole and happy person too and she will most likely support your hobby. The resentment might even be replaced with joy for you if she feels she can let go of that grudge without sacrificing part of herself. They key of course is effective communication. It can be really hard to bring it up but working it out is really worth it!
So that is my "Dear Happy" advice for today....lol. Sorry if I offend, just offering my personal experience.
Best wishes to all!