The answer is “yes, we do, when the existing custom airplanes are already getting near the end of their lifespan and will be quite old by the time their replacements are ready”.
$4 billion would most certainly buy a magnificent airplane or three, but Trump pulled that number out of his arse. Right now the only tangible cost Boeing is charging the government is $170 million for a feasibility study. There is no $4 billion airplane being discussed.
