I would think our space program more resembles locomotives of a long time ago. Certain fundamental physical constraints are standing in our way as far as very fast propulsion, but you've got a point -- who knows. However, I don't think it would be a waste of money. The costs are fairly minimal compared to what it will take to fix various social problems. :)

Also, worry about population won't help too much. Hopefully if the rest of the world gets industrialized the population will level off. Or we'll start eating each other. Either way...