The Russians lost their Lunar vehicle on the launchpad (and IIRC had it not failed they'd have beaten us to the moon), and we were entrenched in the Vietnam War and needed the money.
There was reason why no one dared to travel to Mars on manned mission.
Both sides lacked (and I think still lack) the technology to send men on the yearlong mission and bring them back. In addition it would be horrendously expensive.
I don't like to ascribe supernatural explanations where perfectly reasonable natural ones exist. And I'm perfectly willing to eat crow on 12/22/12 if I'm wrong.
QUite a number of folks insist we have had bases on the moon and Mars for a long time in cooperation with a particular race of ET's.
What do I know.