>If you make gigantic claims about some terrible disaster that might happen then I think you have the onus to give even one plausible explanation of how.

Supposing I warned in 2015 that the world is awfully vulnerable to pandemics. You're not going to take me seriously until I try to predict in advance every aspect of how a pandemic like COVID-19 would unfold? Why? What would that achieve exactly?

You haven't given any strong reason to believe wiping out humanity would be difficult. Your big argument seems to be that you couldn't think of a plausible scenario, in two minutes. But many major historical events occurred which weren't necessarily possible to anticipate with two minutes of thinking.

Design a virus that is perfect for transmission and killing the host slowly, and seed it in a few hot spots? I don't really understand why you can't wrap your head around that, it doesn't even require a lot from the AI:

1. Control over some automated bio research lab (be given access, or hack in)

2. Access to drones that can deliver the payload (or manipulate humans into delivering it themselves)

On the intelligence side, you just need an AI agent/swarm capable enough to design viruses better than we can and evade detection for long enough (already plausible.)

I agree that this "AI will kill us all" narrative is some kind of fantasy horror fiction, but I can't deny that given the right amount of access, AI can do a lot of damage.