C'mon, every president makes promises to get elected. Some of them have a cooperative Congress and can make those promises reality. Most don't.
Classic rule of politics - of life generally: don’t promise what you can’t deliver. Trump apparently thought that dealing with Congress was going to be like wheedling real estate investments out of little old ladies, or enticing apprentices to embarrass themselves on TV, or scam wannabes into paying for Trump University.
Well, it ain’t. Those groups are all little league compared to dealing with Congress.
If he ever bothered to think things through, and pay attention to details, he’d have known that, and would have made his promises accordingly.