It is also asymmetric. If you announce your presence, even if 4 out of 5 civs that notice you don’t annihilate you immediately (but they probably should), the fifth might. It’s just a probability game, with permadeath.

So hiding is the most rational - the only - strategy of survival.

This is a paranoid and cynical strategy that doesn't win out in the known history of life. What works is grow, expand, mingle, maintain - assimilate but don't annihilate.