Like everything, it's all a matter of perspective.
If you think about it, everything is in space. We just happen to be on a planet that's in space.
In all seriousness, we, and everything we know, will end up in space eventually. The earth is not expected to last forever--something will devour the planet (probably the sun) several billion years from now. Such are the ways of the universe!
Elon Musk is right, for humans to continue we need to become a multi-planetary species. We might as well start figuring it out now because we can. If we stop wars and other stupid destructive things we can make more progress quicker.