I have 2 things I need to say in response to this. 1 is that good comedians also tend to have mental health issues. Depression and substance abuse (particularly alcohol) are extremely high among professional comedians. That being said, I don't dislike the idea of having a depressed alcoholic for a president. They couldn't do much worse and they'd probably do a lot better.
As for the 2nd part, I think Douglas Adams said it best:
“The major problem—one of the major problems, for there are several—one of the many major problems with governing people is that of whom you get to do it; or rather of who manages to get people to let them do it to them.
To summarize: it is a well-known fact that those people who must want to rule people are, ipso facto, those least suited to do it.
To summarize the summary: anyone who is capable of getting themselves made President should on no account be allowed to do the job.”