...Alexander Elder, in his 1993 book Trading for a Living, presented a more skeptical view, later used as evidence by Gann doubters. "Various opportunists sell 'Gann courses' and 'Gann software.' They claim that Gann was one of the best traders who ever lived, that he left a $50 million estate, and so on. I interviewed W.D. Gann's son [John L. Gann], 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."Apparently he was quite good in his day. But if you read, and try and follow him, today, will you gain anything?
https://www.investopedia.com/articles/investing/091615/mysterious-life-trading-legend-wd-gann.asp