The "special sauce" is that he's seasoned television personality first, and a politician at distant second. He knows what looks good on stage. He's got the theatrical instinct (arguably the only real skill he has). He's willing to court an audience, there's an audience that wants to be courted.

We're a TV-brained people, us yankees. It's how we get our ideas of the world. But there's a contradiction that comes with it - we can't help but compare the television show to our actual lived experience. For a lot of people, Donald Trump gives them permission to do what they were going to do anyway. He sells them the dream that the disconnect between television and lived experience will go away if they just keep watching TV. Specifically watch him. And buy his merch.

Great Man Theory would see him authoring events. He's done no such thing. Events author him - he just happens to embody a pretty core contradiction in american society. If he never existed... someone else would fill the niche. Probably not in the same way, or to the same timetable. But the potential would still be there, would find someone to fill the void.