The text below is quoted from a [1990 article](http://www.scientificamerican.com/article.cfm?id=mandelbrot-set-1990-horgan) in Scientific American dealing with the discovery of the Mandelbrot set. The emphasis at the end is mine, and the point (subject to debate) is that although Mandelbrot had a PhD in Mathematics, he did not do serious research related to his discovery of fractal structures. He is of course given due credit for the paradigm change he created.

> Sullivan, who has also been acclaimed for his studies of the Mandelbrot set, calls himself "sort of a defender of Mandelbrot." Mandelbrot deserves to have the set named after him, Sullivan says, because his efforts brought the set to the attention of both the public and of the pure-mathematics community. 
>
> The fact that it was only "by coincidence" that the set proved later to be mathematically significant, Sullivan says, in no way diminishes Mandelbrot's achievement. "That's the wonderful thing about mathematics," he adds. "<i>Even amateurs can make important contributions</i>."