Because God isn’t real and the universe isn’t designed to support life, that’s just an accident of chemistry and opportunity.

That said, it is a bit of statistical certainty imo. What isn’t certain is that it’s intelligent and conscious, that FTL travel is possible, or that it’s within a million light years of us. Hell, the most reasonable (imo) hypothetical numbers of the Drake equation aren’t even that great for there being intelligent life within our species lifetime in the Milky Way, and that’s with assumptions like “all planets capable of supporting life do.”