How do we know the probability of chained events required to start life in any given planet with potentially suitable environment?

How do we know that the probability isn't something like 0.01 to the power of some very large number, far higher than amount of total planets etc?

If we don't know the exact mechanism for all we know the odds could be infinitely low, even so low that even after billions of big bangs only 1 would have had life occurring anywhere at all and lower than that. Because maybe the first life form literally had to appear spontaneously from bruteforce chemical reactions with such low odds of ocurring.