yeah those idiots at NASA that landed a buggy-sized nuclear powered rover on mars. they have a pretty good track record. i tend to put more credence in what NASA has to say than you. nice analogy though.
You're missing the point. NASA is not one thing. The NASA scientists and genius engineers who actually build all the cool stuff say it'll cost $2 billion. Administrator Bolden, the political appointee who's in charge of figuring out how to pay for it all, says he doesn't want to budget more than $1 billion. I guarantee you he has no good ideas about how to make the mission fit into a $1b budget: he himself says "that may or may not be possible."