Maybe it's hindsight talk, but I would argue that going to the moon and back is a very different goal from "colonizing Mars". Landing on the moon is a one-shot thing compared to the longer time frame of Mars colonization. Also at the time it was spearheaded by the actual US government (in a weird political race against the USSR, granted), not by some billionaire playboy like now.

So I'm not sure it was warranted to go land on the moon and back, but it was an American public good, of which there isn't much anymore.

And Musk isn't spending a dime of his own on Mars, the reason he's publicly promoting this goal may also be because he stands to earn even more money from public subsidies than he currently does with his SpaceX venture.