Trump ran on his identity as Trump. The man successfully "built his personal brand" before that was even a thing. I don't know of an earlier example of "famous for being famous" either. He really is in a class by himself and he objectively proved that by winning the Presidency of the United States. One can actively dislike his personality and policies while still being honest enough to acknowledge his cultural impact.

Trump may be famous for being famous, but the idea of him being a business magnate has always been a core part of that image. That doesn't detract from the significance of his ability to appeal to people far from the usual coterie who read the Economist and who knew about the Trans-Pacific Partnership before 2015, but it does support the original argument that "entrepreneur" qua "business[wo]man" can be a gateway to high social status.