[quote=Sauron The Dark Lord]
I would imagine that the Aliens would want the resources, which is the only reason they're on our planet, the only legitimate one, at least. That would keep them from ruining the entire planet in an instant.Once again, I do not mean to be offensive, I'm working on my CS as we speak.
[/quote]

Earth is hardly unique when it comes to plentiful resources. The aliens could obtain the resources present on Earth by strip-mining uninhabited planets and free-roaming asteroids.