I strongly beg to differ. Building is the easy part. It is the political will that isn't. Try to build a train in California and it takes decades and you have a hundred different entities sabotaging you. Put five more lanes on a freeway and no drama, it just happens. We got to the moon when the political will was there but the engineering was still basically science fiction but once the political will dried up, even though the engineering was solved and 'easy', we couldn't get back. History is full of these examples.