I used to have a friend called Doug who made a similar argument. Doug had diabetes, but would drink Coke and smoke cigarettes.

Doug pointed to several heart attacks as proof he would survive. And that worked for a bit, but the sixth one killed him.

Now, humans are more adaptable than cockroaches, even. I actually think it's likely that most of the world will survive the initially collapse.

But if we burn all the fossil fuels, the resulting CO2 levels would render us incapable even of rational thought.

I am not saying we'll be extinct for sure, or not, in the near- or medium-term. (In the long, long term entropy will tear everything apart.)

I am saying it is quite possible we will actually kill ourselves off entirely, not that it's certain nor that it's impossible.