I highly advise you to find some sort of management position with a flight school first to get to know how the business works and also, if you haven't already, get a degree in business or something. Aviation Administration or similar would be good to start an FBO and can be achieved over the internet so it could be something you do while you run the FBO. But don't go into the aviation industry without any knowledge of how to run a business, you won't last a month. You also need to consider that most businesses don't just make money from the classes, they sell fuel to other FBOs in the airport, have pilot shops, maintenance shops etc. At least the ones that have been around for a long time. I suggest you get a good amount of starting capital and some to spare especially in this troubled time. I suggest you start writing a business plan and look for investors. If you are a CFI, you can rent a small hangar and purchase something cheap like a 152 and give classes independently.