I'd agree that the initial push into space and the moon did accomplish great things insofaras getting the physics of the previous 200 years engineered into modern society. There was a lot of great ideas floating around that had little chance of developing until such need as what the space program initially compelled us to produce. Those days are for the most part done. There are still a few novel physics concepts to iron out that almost uniquely require a platform such as space exploration, but there will be no big leaps and bounds like what we saw going from the early 50s to the 70s.

I believe the far bigger cost for this country in the Vietnam conflict/war/police action was the loss of a lot of good men for purely political reasons, in the end failing miserably to meet our objectives.

As for the here and now, I believe there is an abundance of much more suitable peaceful and benevolant objectives upon which we can focus our energies as a national goal that have nothing to do with space exploration, and for which continued investment in space exploration at this time would seriously detract from.