Why don't they just live in space?

Yeah but if you got the tech to travel interstellar distances you got the tech to live in space one way or the other, and that's true even if you're in suspended animation

When it comes to living in space, I think it's actually way more likely we'll do that then live on other planets.

The amount of energy it takes to travel interstellar distances within a human lifetime is huge. If you have access to that kind of energy, you absolutely have access to enough energy to make something like an O'Neil cylinder, a gigantic rotating space habitat that is essentially a city in space. If you've got the tech to build space ships that are traveling at .1c through the interstellar void, you've got the tech to build space stations that meander across a solar system over a period of centuries.

Basically, any alien species capable of invading earth "for resources" would have a far easier time just getting those resources floating around out there in space. That's one of the points in the Fermi paradox. If aliens are out there, we SHOULD see them doing stuff like making Dyson swarms, gathering asteroids, etc...but we don't.