People pay huge fees for courses today, I don't think that necessarily means they are worth the money. Did Gann ever claim to have made 50 million dollars or is it just the people selling his trading materials? Are you sure about your facts? I found this quote from a search and hope it is correct. Perhaps someone who has the book can confirm it:-
Quote from 'Trading for a Living' by Alexander Elder. p23
"Various opportunists sell 'Gann courses' and 'Gann software'. They claim
that Gann was one of the best traders that ever lived, that he left a $50
million estate, and so on. I interviewed W.D. Gann's son, an analyst for a
Boston bank. He told me that his famous father could not support his family
by trading but earned his living by writing and selling instructional
courses. When W.D. Gann died in the 1950s, his estate, including his house,
was valued at slightly over $100,000. The legend of W.D. Gann, the giant of
trading, is perpetuated by those who sell courses and other paraphernalia
to gullible customers."