Your first paragraph there is about how life spreads around on a planet once it's arisen. It doesn't have anything to do with the chance of life arising in the

Your first paragraph there is about how life spreads around on a planet once it's arisen. It doesn't have anything to do with the chance of life arising in the first place. We have evidence of precisely one origin of life event -- all life on Earth looks to derive from a common ancestor (called "LUCA"). We don't know how common OoL is on a planet like Earth. We cannot use the fact it occurred here to conclude it's likely, since if it didn't occur here, we wouldn't be here. Our mere presence to ask the question biases the observation. The less likely it was, the more biased the observation. Second paragraph: what is this supposed tendency of nature not to repeat itself? The universe is full of objects that are unique arrangements of atoms, not repeated anywhere else. Indeed, all but extremely small objects are very likely to not recur. So this supposed universal property of repetition doesn't appear very universal. Proposing that Origin of Life is in the subset of phenomena that do repeat is just begging the question. As for "what basis is there for thinking it can not exist anywhere else?", that question is relevant only if I were asking you to believe life is not common, not if I were asking for justification of statements that it is common. The opposite of belief in X is not belief in (not X)!