He does have his flaws, such as his issue with flip flopping.
I agree that's a flaw but I don't see it as traditional flip flopping. Other politicians change their minds, often to pander to voters or some interest group or something. However both before and after the flip flop, they had a firm stance which they thought thought through and understood.
Drumpf on the other hand is a salesman, he just says whatever the hell comes into his head that he thinks the other party wants to hear at that moment. 15 minutes later when he contradicts himself, it's not that he had a change of heart or now has a different view -- he just thinks his target needs to hear something different for him to get what he wants.
What he truly believes on anything is a mystery. He probably doesn't actually believe anything, other than him wanting to get his way.