> A very unlikely planet-killing asteroid

There's heavy evidence there's already been a mass extinction once from an asteroid.

> I can live with the odds.

You may be able to, but a lot of people don't want to gamble the existence of the human race if there's a chance we don't have to.

You may also live with the odds of no backup to a database, but others here will attest to the importance...

> Let's face it: space exploration is cool, that's all. No need to find excuses :)

Well, you asked "why do this and not focus on Earth", so I gave you one reason.

But yes, I agree, space exploration is cool all on it's own, so I don't see what the complaint is.