Which retroactively gets them assigned 'misfit' status, as a sort of honorary name. Franklin, Churchill, Einstein, Noether and Darwin, to name just a few, all weren't misfits. They were simply eminently capable people that believed in themselves. You don't need to be a misfit to achieve greatness and we don't need to call everyone that achieves greatness a misfit.
Whether or not Einstein was a misfit, the physics establishment considered his ideas crazy (see Thomas Kuhn's The Structure of Scientific Revolutions). By definition, a misfit is one that doesn't fit into the mainstream.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. -George Bernard Shaw
By definition, a misfit is one that doesn't fit into the
mainstream.
I don't think one becomes a misfit by having and defending unique insights. I have a friend that has a Ph.D. in philosophy. He tends to say things that take some time to process and may initially cause a "what?" feeling. As any Ph.D., he did his small part in changing our understanding of the world. I wouldn't call him a misfit, just extraordinary.
Concerning that quote by Shaw: I believe taking that literally is mistaking a funny quip to make you think for a deeply profound eternal truth. Shaw does not seriously intend to say that e.g. Churchill was not a reasonable man.
I actually own a copy of Kuhn's book. I found it very enlightening. He's not a misfit either.