With intelligent life and the development of sufficient technology, a situation will inevitably arise that will deaden the will of life to expand outwards and instead retreat inwards, perhaps dwindling towards extinction.
INCELS might be the first development. With increasing hostility between the sexes along with improving virtual technology making it not worth it to have actual physical relationships. Soon humans may all happily fade inward into an opium-like virtual fantasy world with artificial intelligence meeting our every desire.
As a rule, the same thing may happen to EVERY intelligent lifeform, and thus we see nobody out there in the billions and billions of star systems.