I'm pointing out the fallacious reasoning behind your view that with enough chances, it is inevitable that every possible outcome occurs at least once. That does not necessarily follow, simply because it is possible to generate events of infinitesimal probability, simply because n! grows much faster than x^n. That's just plain math.

Turning to whether the rare earth hypothesis itself is correct or not, I don't actually have a strong view on this. I just know that you can't reason your way into disproving the rare earth hypothesis simply by saying "the earth is possible and therefore common, because everything that is possible is inevitably common."

I don't see how else this could be anything but probabilistic. Unless you're saying every star is the same size as the sun and every star has an earth-like planet orbiting it in he habitable zone, the probability of those things is obviously less than 100%. We can already observe counterexamples that proves those aren't 100%.

So if you want to argue that there's no way the probability is less than 1 in 10^21, fine. Then we're having the conversation about the actual probabilities. But my whole point, since my first comment in this thread, is that it is not enough to say "I think there are 10^21 planets so life is inevitable." That's not sufficient to support that conclusion.

Debate whether a large moon, plate tectonics, a magnetic field, an atmosphere, an ozone layer, a Jupiter-like neighbor, a G-type star, and what ratios of specific elements need to be present on a planet to qualify. I'll leave the actual estimates of those probabilities to others. But each of these factors has a non-100% chance of happening on any given planet, and it becomes a question of whether the probabilities stack in a way that overcomes the sheer number of stars and planets there are. And that's the thing I'm sure about, that you simply can't ignore the factorial expansion of those factors because you think that there are enough planets in the universe to make that irrelevant.