I had no ground school, just bought books until my instrument rating. Worked great for me. I even got my instructors rating reading a book. I went to take the test because I wasn't sure how to study for the test because of all the philosophy of teaching BS. Well, I passed so never learned it. Taught my self aerobatics out of a book, then taught it for Art Scholl, one of the best, with his school. Books are great if you can do it without someone to help you.
My first job when I got my commercial license was crop dusting with zero training. Loved it. After soloing with 5 hrs total I was doing solo spins and finally a loop solo before 10 hrs. It was fun learning that way. With 5 hrs back then you could fly cross country anywhere you wanted to go so would go out and land in the desert on the sand just for fun. I had a AAA map for nav, no aviation charts and did just fine. That 15 degrees variation didn't bother me a bit because at that time I didn't know what it was. Well guess it was in one of the books.
Ended up flying with the largest airline in the world at the time flying a B727. Ended up in the B757 and B767. Funny how things can end up mainly reading books, isn't it.