In his last few debate performances, Carson looked very sedated and tired. It looks like he wasn't able to handle pressures of running for president, and therefore, he wasn't able to handle the pressure of being president. I did see a 2013 speech on Youtube that was excellent. He was full of life, energy and inspiration and I can see why many conservatives wanted him to be president. I love how he emphasized education, worked hard, had positive moral values and escaped poverty.
Carson was scant of administrative experience and dense on policy, so I never took him seriously as a candidate. However, I do think he has some political career ahead of him. He has a lot of good things to offer whatever job he goes into. Just not president. I think our society today is short on role models. While I don't agree with him politically, I admire him as a person.