even if we could 'perceive' them... how many are stupid enough to broadcast their location... I mean what if there IS some sort of galactic predatory species that beat everyone else in the timeline? What if they're just waiting for signs of life - to squash the competition.

I think it was Carl Sagan who once said something like: it doesn't matter how 'well-meaning' an alien civilization is... it usually doesn't end well for the less advanced one... case in point: American Indians. (paraphrasing)