How do you know that $4B is reasonable? You haven't a clue. Are you in business? I doubt it, otherwise you'd recognize what Trump is doing. It's called getting a better price. New sheriff. Old way of doing business is ending.
From what I understand, there wasn't even an agreed upon contract and the $4B number was something Trump came up, made up, fabricated..... Donald is Donald. He lives in his own parallel universe.