We do many costly things for non economical reasons.

In the end, economics is an instrument to our real goals and these are psychological.

For instance, we want to earn money not for the money on it self, but also to feel some positive emotions, including security, independence, freedom to do what we want, etc, and not just goods.

The USA and the Soviet Union spent billions on the race to the Moon just trying to show the world what was the best political system.

Musk likes to talk about the idea of converting us on a two planets species to rationalize his quest, but he won't see it on his lifetime (unless he starts investing a lot of anti-aging investigation or brain transplant, etc.).

Sometimes, he confesses that the real goal is to do inspiring things. He means historical things. He is chasing his place in History, trying to reach out immortality.

And I have nothing to say against that. It's people like him who took us from our stone age caves, since most of us haven't done and won't do anything really important during all our life.

We want to go to Mars because it would make us proud to be humans like nothing else. And this is why we are going there sooner than to any asteroid, even if it had many valuable minerals.

We would go there even if the voyage didn't bring any real technological innovation.

No doubt, if we waited 50 years more, we could go for much less money and lesser risks, but why give the glory to our sons and grandsons?

Since our fathers and grandfathers left this opportunity, let's take it ourselves.

The way I use the word "we" and "us", even if I won't have any role on the voyage, is similar to the way people talk about football successes: they never say their club or country won, they say "we won".

It's this individual/collective appropriation of the successes of other people that give so much psychological importance to events that in reality are irrelevant to our life, like going to Mars.

It will be if all of us had a role on this historical success to humankind.