He could promise voters anything he liked, and because he has no political history, people just believe he can back it up. Or that maybe he might be able to achieve all of his promises.
If he had had any political history, even a small one, voters would have known that Trump can not do more than other politicians. He is not gonna accomplish even 5% of what he is promising. Obama had the Republican Congress and Senate against him. Trump will both have the Democrats *and* the Republicans against him. Trump is not part of the Republican Party. He has no contacts there, he has nobody loyal to him, he is basically alone. He won't be able to do anything, unless the same-old, same-old Republican career-politicians tell him they will allow it.
You are up for 4 years of Republican government. And it will have nothing to do with what Trunp wants or promised.
And on top of that, you'll have a SCotUS filled with 6 or 7 utter-retard medieval religious-crazy nutcases for judges.
I think 4 years from now, people can make a good case against James Comey. For treason. Off with his head. He deserves it.