His Secretary of State has called him a moron.  Mental Health experts have looked at his behavior and agreed that he is a narcissistic egotist unqualified to be POTUS. Even many Republicans agree with that.
Trump contradicts himself from day to day about important policy matters. He is a reality show star,  skilled at fooling a certain segment of the public into thinking he is a great man, and playing on the resentment of uneducated people against those who are well educated.