[argumentum]

The number theorist, Ramanujan, had only one Cambridge degree, "B.A. by Research", which was later renamed as "PhD". It was awarded after he had published important work with two of the greatest English mathematicians, Hardy and Littlewood.

If you delve into history, there are innumerable examples of achievement through non-traditional channels. Lincoln didn't have a law degree, for example. In the 20th century, auto-didacticism (teaching yourself) became less common .. here's hoping that that trend is reversed in the 21st.