The dark forest solution to the fermi paradox theorizes that there are a lot of species in the universe, but we don't see any because if you make yourself known in the universe, you get killed, either from an apex predator or other species staying quiet. The second one is interesting because according to logic, the species who shoots first survives. This is similar to the nuclear bomb paradox: Whoever launches bombs first wins, because you can destroy a whole country with a couple, leaving that country not just incapable of retaliating, but dead. If we can't understand an alien species, and they can't understand us, they don't know our intentions, and the safest move for them is to annihilate us.