the earth is just a speck of dust compared to all that exists and all that is possible. It would be absurd and illogical to think that there isn't intelligent life elsewhere. I doubt that we'll be visited by aliens. I'm sure that other civilizations would exploit their resources in a technological race and fuck up their ecosystem and doom themselves back to the stone ages before getting to the point of intergalactic space travel, kind of like how we are doing.

If there were a race of aliens that were capable of contacting us, they would have to be morally superior to achieve advanced technology without killing themselves first, and as such they would probably have moral statutes precluding them from contacting us because we wouldn't be ready and it wouldn't help our productivity. Kind of like the prime directive in star trek.

On the other hand, they might decide that it would be morally responsible to inform us of our inevitable demise, unless they've tried that with other races and no one listens