Change the paradigm.
You don't need water, oxygen, etc... if you don't send humans. Private enterprise will do the cost analysis, and I bet they will send very sophisticated robots first. Go to the Asteroid belt to mine for things, go into low/medium orbit to develop new materials and manufacturing processes, etc... All with a focus on what is the best return on investment, not what political whims are fashionable.
I agree with others that Kennedy's speech about going to the moon was brilliant, but we were developing heavy lift capability anyway for the military, and maybe starting a 'space program' deflected some of the criticism that would have come about of we had developed the heavy lift capability, etc... with only military interests in mind.