It is impossibly expensive and lacks the kind of popular support required to get the 1969 mission of the ground  To make the kind of funding this project would require available, massive public and political will would be needed. This simply doesn’t exist.  The Cold War mentality of the ‘60s provided a justification. Having been beaten to get a man into space, there was an imperative for the American people to beat the USSR to the Moon.  No such justification exists for going the at all now, let alone going back. The only country in the world with both the technical and financial resources to do this, the United States, simply doesn’t have the political stomach to do it.