Saying that the chances are 1 in a 100,000 doesn't imply that life happens once per 100,000 stars, just that that's what'll happen on average. You can roll a di

Saying that the chances are 1 in a 100,000 doesn't imply that life happens once per 100,000 stars, just that that's what'll happen on average. You can roll a dice 20 times and not have a six come up. But yes, it's difficult to figure out the probability of life occuring if we only have a sample size of one. On the other hand, nobody's found anything particularly special about the Earth's placement or chemical makeup, other than it's rocky and has liquid water. This is why exploring the other planets in our solar system is important. If we explore Titan and find weird, hydrocarbon-based fish which evolved independently to life on earth, or under the ice on Europa, then it tells us that the probability of life evolving is not that small, and we can up the estimate of the probability of other civilisations in the galaxy.