I know the classic view of CoC is that everyone dies in the end as the world is destroyed, but that's because it's fun to do that at one-shots in conventions! Actual campaigns aren't like that at all. I've run several, and they overwhelming are about the heroes facing barely understandable cosmic horrors and saving the world.
I've railed against the summation of Call of Cthulhu as "that game where you go insane, die, or both" as I believe this harmful and more likely to drive people away from the game. But CoC is a horror game and every game I've participated in, as a Keeper or an Investigator, has been rather bleak. But I've only had one campaign end with a total party kill. Well, one of the characters ended up giving birth to herself so maybe it wasn't technically a TPK. (Cthlhu can be weird as well as bleak.)