The reason we have no contact with aliens is that by the time intelligent beings become technologically advanced enough to colonize the universe, they realize they're not that important and decide to let events run their natural course elsewhere without any intervention on their part.
After a certain level of technological development, colonizing for resources is meaningless. A single start provides more than enough energy to achieve anything they would reasonably want to.
They know that there are billions upon billions of isolated worlds that have developed intelligence one way or another, without having to explore at all, just by knowing a lower estimate of the size of the universe and basic physics and probability theory. So even if they go extinct, it isn't going to matter much in the grand scheme of things.
They focus on their own lives and existence rather than paranoiac assurance of the survival of their species.