Human extinction would require a malevolent AI willing and capable of waging total war on a global scale. That sounds like sci-fi to me.
The rate at which species are going extinct right now due to human activities is unparalleled. And I don't remember total war on all the living things being declared by humans. The result is just by product, not the intent.
“The AI does not hate you, nor does it love you, but you are made out of atoms which it can use for something else.”
The declaration of war was called "manifest destiny". But not just on animals, genocide of tonnes of other human cultures and ethnicities too.
there is a phase where human being are in control of ai before it becomes fully independent. That phase is critical.