I think human extinction through human stupidity or hubris is much much much more likely than through an unpredictable path down general AI.

For example, some total whack job of an authoritarian leader is in charge of a sufficient nuclear arsenal and decides to intimidate an adversary by destroying a couple minor cities, and the situation escalates badly. (stupidity)

Or we finally pollute our air and/or water with a persistent substance that either greatly reduces human life span or reproduction rate. (hubris)

I think either of the above is more likely to occur, and I am not commenting on current world events in any way. I think when something bad finally happens, it is going to come completely out of left field. Dr Strangelove style.

And the last of us will be saying "Hmmm, I didn't see that coming".