We can't use them now, but that doesn't mean we won't in the future.

Once our technology reaches the point at which terraforming is possible we'll move out and start colonizing other planets.

We'll probably start with Mars -- it's fairly hospitable right now compared to the alternatives.

It's my understanding that we could start living on Mars fairly soon, but it's too expensive and there's no incentive to dump the billions of dollars necessary to fund such a project.

You all should look into SpaceX!

God was bored