Could it simply be that he's not a great speaker because he's not a career politician? Most politicians are adept at thinking on their feet (obviously Abbott being the exception that proves the rule) and bullsiht their way through interviews and manage to crowbar answers into questions that were not even asked.
It seems to me Trump doesn't possess this skill - doesn't make him a moron or insane.
It irritates the bejesus out of me when people refer to him as a moron, an idiot etc...you do not become a billionaire, head an enormous empire, employ 000s of people and become the most powerful man in the world, by being an idiot or a moron. If it were that easy everybody would be able to have a go, rather than throwing out the 'moron' insult behind the safety of their keyboards.
I really couldn't give a toss about Trump one way or the other, and quite clearly he very divisive, but to question his sanity and his intelligence is wrong.