Carson is an example of an idiot savant. Extremely smart and capable in certain aspects of his life, while extremely dumb in other aspects of his life.
That he and Trump, neither of whom is a serious candidate nor remotely qualified for the job by virtue of either experience, knowledge or temperament, are leading among Republican voters says much of what we need to know about the current Republican base.
At the end of the day, I suspect Rubio will get the nomination. Fringe candidates frequently do well early on but simply can't sustain it. But, to the extent that these two buffoons continue to shape the Republican Brand in the minds of rational voters (e.g. not Teabaggers), I'm all for it and wish them the best of success.