My post from several years ago on the Efficient Berserker is very popular and I wanted to extend a few ideas.
Suppose there are many intelligent alien species in the Milky Way and most of them believe in the Berserker Hypothesis. Maybe they believe because of evidence, or maybe it's just speculation.
If I believed in this I would hunker down and make sure that my species were as invisible as possible. So this can explain a portion of the Great Silence. Species want to be invisible because bad things can happen when they are found.
This is like being in the French Resistance during World War II. How do you go find other patriots without exposing yourself to the Nazis?