Truthfully, I don't know anybody who talks like that.
Go to New York sometime!
Go start a Cruz thread.
Pay closer attention, and I think you'll find that more people talk like that than you realize. Maybe not as badly, but many people frequently start one sentence and finish another when speaking in ordinary conversation. That's what's going on with Trump. He does it more than most, but most us do it to some degree.
Trump doesn't have a stump speech memorized. He just says what's on his mind, as it comes to him. The good thing is that over time, it's really hard for someone like that to hide their true thoughts. They will eventually spill out.