We don't know that any of those conditions are necessary. Right now what it looks like is certain chemistry, which happens to be pretty common, an energy gradient of sufficient magnitude, and relative stability.
If we look at it as crazy coincidences, we can say that the earth is in a very unique state due to the crazy coincidences such that theres nowhere else just like it, but then, theres nowhere like anywhere else and everything that exists is the result of crazy coincidences. So, combinations of crazy coincidences that create very unique places are pretty common, ubiquitous even. So there's likely a lot of very unique places out there with very interesting processes going on.
I don't know if we will ever discover life. I don't know if we will ever observe another intelligence that spontaneously developed. But one thing I'm certain of, there are things going on out there that are more interesting than dead rocks circling even bigger dead rocks.
My theory on this is that intelligence, language and culture are surrounded by very high local maxima and we only got over the hump and down into our minima by incredibly slim chance.
So our original evolutionary advantages were persistance hunting & rock throwing (ranged weapons). This gave us such a huge advantage that we had enough excess energy we could start to develop bigger brains, language and culture (tools). For it to be possible we needed:
* Huge evolutionary advantages (rock throwing? fire to cook? walking upright? sweating?)
* Vocal chords that would let us develop language
* Hands that would let us make tools
And once we have that we can start to evolve intelligence and shared culture. But for a very very long time this was evolving a trait that is an actual hinderance. So we also need for that to be our 'peacocks tail'. A costly trait that is selected _for high cost and total uselessness_. And that trait could've been practically anything else!
Imaigne all the worlds where ranged weapons are developed by a species which just can't do language. Or where they can't make tools only throw rocks they find with their evolved longbow like limbs. They'd conquer the world but that would be it. And that world is now too well optimised for another animal to develop intelligence, they can't afford it.
If this is the case life could be wildly abundant but 'intelligence' more or less unheard of. This is infact what we see in the historical record on earth, there were many epocs of dinosaurs, as far as we know none of them shaped rocks for throwing, had language or developed cultures. In the time we've been around no indepdent intelligent species have evolved (we only see evidence of ones with a common ancestor.)
I think the drake equation suffers from the same fallacy that seems to beset everyone talking about AI. Intelligence is over-rated, it is not a linear thing or a super power where more of it is always better and can solve any problem. It's incredibly costly and often quite useless. Our actual problem solving is more down to trial and error at the level of culture than we like to admit to ourselves.
If we look at it as crazy coincidences, we can say that the earth is in a very unique state due to the crazy coincidences such that theres nowhere else just like it, but then, theres nowhere like anywhere else and everything that exists is the result of crazy coincidences. So, combinations of crazy coincidences that create very unique places are pretty common, ubiquitous even. So there's likely a lot of very unique places out there with very interesting processes going on.
I don't know if we will ever discover life. I don't know if we will ever observe another intelligence that spontaneously developed. But one thing I'm certain of, there are things going on out there that are more interesting than dead rocks circling even bigger dead rocks.