Well, when I quit flying I wanted to build software and avionics for the aerospace industry, it didn't work out, you need to be ready for extremely long stretch

Well, when I quit flying I wanted to build software and avionics for the aerospace industry, it didn't work out, you need to be ready for extremely long stretches of time without any income to cold start something like that. I even started building some toys, I built an artificial horizon and was thinking about building a GPS navigation for private pilots (garmins are too expensive). I even pushed to github some of that code. (https://github.com/eduardordm/inav https://github.com/eduardordm/inav) In that time I found the path to actually have some chances of succeeding without expending millions of dollars: start as a sub-contractor. You see, flight in general is a huge industry. We all praise Elon and SpaceX but we tend to forget that there are hundreds of smaller companies that made his venture possible. From QNX to a small paint factory in Florida. So, concentrate in getting involved by doing work for those smaller companies, with time, you will have the expertise to open your own.