It has puzzled me too. I think it’s a combination of:

• above average raw charisma (people subconsciously want to relate to him)
• VERY generous / manufactured audiences
• our strong subconscious tendency to want to laugh along with others
• deliberate abuse of the “this is so funny I can’t help but break character” move, the most egregious and hateable thing the man does

People look at me like I slapped their mother when I say I find him 0% funny or likeable.

You’re asking this in a nation where tens of millions think Donald Trump is president material.

They either can’t see it or they see it perfectly well and they like what they see.

You may find either or both of these disgusting.

This logic can also be applied to elections.