The reason is that AI could do it a LOT faster than we could. See the singularity. Additionally, AIs could decide that humans are a threat (or a resource to u

The reason is that AI could do it a LOT faster than we could. See the singularity. Additionally, AIs could decide that humans are a threat (or a resource to use) and that could be dangerous to us. I agree, without AI we might be doomed anyway, because of how we are dealing with the current existential crisis of climate change.