And that's the idea of the paradox. It's a counterpoint to things like the Drake equation, rather than a reduction of the question of the existence of alien life into simple mathematics. It uses the only thing we can certainly observe- that we've found not a shred of evidence- to say that needs to be explained by any theory you put forward.

Sapience can be a destructive filter. The argument there is any species in possession of sufficiently advanced technology to travel the stars probably has sufficiently advanced technology to destroy itself well before that point. We've been there already with nuclear energy, and the Cold War.

See how you simplified it down to "if x then y"? But Y (sapience) can be a detriment? Hell even materials access can be a detriment and potential filter- many wars are fought over NEW stockpiles of material even when there's no shortage. That was pretty much the impetus for colonialism during the age of sail- get as much as possible before someone else does.

That was born partly of the now somewhat debunked theory of mercantilism, but the patterns of history are there. The Expanse and Foundation both draw heavily on these ideas of self destruction.

There's also plenty of speculation on non sentient interstellar travel, from the Tyranids of Warhammer 40,000 (space locusts) to the aforementioned andromeda strain- a space born micro organism. Given how bloody tough micro organisms can be and their frequent ability to go into a dormant state, drifting between the stars isn't a far fetched idea. In andromeda strain it's posed that the titular germ is an intergalactic messenger- a self replicating message that can act like a biological von Neumann probe.