But, as you say, with respect to life (or at least complex multi-cellular life), we just don't know. But the Drake Equation encourages thinking like, even it's it's a 1 in a trillion chance effectively zero!, we'd have all these aliens running around. Because 1 in a trillion = 0 is pretty much what we're informed by day-to-day usage and intuition.
Avogadro's constant is 6.022 x 10^23 [1]. There are a hundred billion sets of a trillion constituent particles in ever mol of anything. A reaction that happens to water once in a trillion years would occur 20,000 times a second for each 18 mL of water.
The other big question is how long technological civilizations last. Ours is less than 200 years old. (A useful starting date is 1830, when the Liverpool and Manchester Railway started carrying paid passengers. That's when powered technology got out of beta.) How long before we run out of cost-effective nonrenewable resources? Probably a few hundred years, tops.
I'd consider as the reasonable starting date, when we discuss about the alien civilizations on the distant planets, the day the radio communication starts to exist.
So we're some just for some 110 years capable of sending and receiving any radio message. If we move to the "capable of receiving the faint message from the big distance" it's more like just some 60-something years.
Also note that as we move to using the digital, high-density, compressed and especially encrypted messaging, the transmitted messages look more like the noise than the signal.
I made that point to a SETI guy who was giving a talk. They were looking for "carriers". Nobody uses carriers much any more. It's a huge waste of power and bandwidth. There are much more efficient ways to get synchronization. Everything later than analog TV is low-carrier or no-carrier. Unless you have some idea of what to look for, the signal looks like white noise.
Which doesn't have to be cleverest thing to do, and maybe we should also be worried enough to care.
To make a computing analogy, maybe taking part in the "galactic internet" without the latest "firewalls" and "spam filters" can be really the matter of life and death for the whole planet ("what you didn't know that we send the 'energy beam of death' to those who don't respect the protocol, well the whole galaxy knows, and you won't do it again, heh, heh" even if we avoid other trivial issues like a galaxy "superhighway" which has to be constructed in our neighborhood or simply that humans are maybe very good to be used as food or work animals from the point of the possible invaders). So we should learn about the others but really try to stay as undetected as we can until we know more. And maybe other aliens think like this paragraph argues too.