I think the main extinction risk is the secular trend for technology to become both more destructive and more decentralised. If that continues, it might only be a matter of time before independent actors will be able to extinguish the human race. And given the distribution of human motivations, if individuals can do it, someone will sooner or later.
I have a harder time believing independent actors can extinguish the human race. Biowarfare/terrorism is unlikely to do so for a variety of reasons, and nuclear warfare only has the potential to do in superpower level conflict, and even then I don't think it's certain.
Being satisfied that some "naked apes" still living could mean a survival, as a biological species, of the probable destruction of current civilization is setting the bar really low.
I don't think it's likely, but I also don't think it's something one can dismiss easily.
Existential threat multiplier? Probably yes.
Because of.....Y2K?