When you think about it honestly, we really don't know anything about anything. We don't know how many planets there are in the galaxy (nor in the universe, nor in the multiverse, nor if there is a multiverse). We don't know what the chances are of a given planet being habitable (nor what "habitable (for all possible life)" means, nor what "all possible life" means). And we don't know what the chances are of life existing on a given habitable planet. So apart from the fact that all of the above probabilities may well be at or near zero, we're barely even capable of articulating the necessary questions, let alone searching for answers.