megalomaniac
The Cambridge Dictionary defines megalomaniac as:
Someone who has an unnaturally strong wish for power and control, or thinks that they are much more important and powerful than they really are.
I can’t imagine whom this might be describing…
Sadly for us, he is the most powerful man in the world. So he doesn’t have to imagine how powerful he is. Combined with his lack of humanity, this is bad news for all of us, not just here at home, but the entire world.