As middle ago people, we can not back to school to lean another 4 years. As flight pilot. But there are many small business need only 3 to 6 month training.
I was F1-H1-GC and was a Sr. Electronic Design (IC) engineer. Now I am a real estate and financial expert.
Business has its own orincipal. Learn the general principal first. Invest something. Work very hard (it is work for yourself). learn the technology (we are much better than those w/o degree. Learn from any one, (from all those w/o degree). Any thing, even the general market is decline, we are better.
I had a friend told me many yaers ago when I was in graduate school. " we are in the top national university and so we are the top in the world".