The pluses and minuses have already been mentioned, so I'll stick to cautions. If you intend to pursue music instruction as a way to make a living, you need to approach it as a business. You don't need to have a MBA to do this, but it would be helpful to write a
semi-formal business plan. You can buy a book on this, or not. By writing it down you will force yourself to be specific about what it is you are going to do, how many hours you will do this or that to acquire additional customers expressed as Plan A, Plan B, C, D, etc. Nobody else has to ever see it, but it will help you organize yourself and make your efforts more focused. Nothing is more counterproductive than traveling down the road for some time to find yourself saying to yourself, "OH SHIT, I didn't think about that!" Having a business plan will allow you to constantly update and tweak it as some things prove better or worse than expected. There is no such thing as a business plan that is right on the money and just needs to be followed once written. Having one forces you and your wife to acknowledge realities, refine specifics as progress is made or not made, and develop alternatives ASAP when appropriate. It also allows you two to agree that the costs and achievements are worthwhile. Every small business owner will tell you that the spouse shares your success or failure whether or not they have any active part in the endeavor. If you are not both pulling the wagon willingly, it will tear your marriage apart. A written business plan continually recombobulated by both you and your wife will serve as a good way of not ever surprising each other with an, "I didn't know about that...". Like getting real quotes on insurance, beforehand...
As to making money in bonsai, the old saw, "Want to make a million dollars in bonsai? OK, first, get two million dollars." Bonsaiists are a lot cheaper than outsiders may think. Buying materials at retail and making a profit on it is hard enough, but buying at wholesale means paying for inventory which can tie up cash and may or may not actually be profitable anyway. Or, even just break-even. Do one thing at a time. Spend money and time acquiring more music customers. For extra money, working on weekends or nights at some ordinary job where others don't want to work could be helpful.
You can do it! Plan Ahead...