There are many examples of those with great talent/accomplishments in one field who had sufficient acumen/interest to excel as amateurs in another field--which in turn they might have chosen as an alternate career path. A few examples:
* M. C. Escher, the great Dutch graphic artist, developed what he called a "layman's theory" of symmetry, which has proven to be in line with classic group theory. Suppose he had turned this interest into formal mathematical training and become a mathematician?
* Kurt Gödel, one of the great theoreticians in physics, at one point constructed-or attempted to construct-a rigorous proof of the existence of God, but was unable to do so (that's a separate thread in its own right). What if Gödel, a devout Lutheran, had instead chosen a career as a theologian? Would he be counted as an equal of Kierkegaard, let's say?
* Groucho Marx frequently noted in his more serious moments that he often wished he'd pursued a career in medicine. How would the world have benefitted from the ministrations of Julius Marx, M.D.?