If we find them first, we have a bigger economy and access to relativistic weapons, we immediately launch them and send probes to make sure they're all dead.
We find them first have a weaker economy and no access to relativistic weapons, we hide and convert our entire industry to be able to make relativistic weapons, 1/4 of the population may die due to rationing.
They find us and have a bigger economy and access to relativistic weapons. We are dead unless we detect them, there may be a small chance for us to run and hide.
They detect us first but don't have access to relativistic weapons and a smaller economy. They hide and immediately start building weapons. There is a chance we may detect them and send human spores off solar system to survive, we may not be able to retaliate however, so our economy would be crippled from Sol being annihilated, run and hide strategy kicks in.
Tldr, you don't want aliens to find you, and you don't want to find aliens
