One could argue that this has already happened: social media is the singularity. The evil AI doesn't have to be implemented entirely in silicon. Indeed, that fact that it runs in part on human brains helps it remain stealthy.
More or less. Human brains are an emergent property of a large number of highly interconnected neurons, so I see no reason something similar couldn't emerge from a large number of highly interconnected brains.
But the thing to keep in mind is that this emergent thing is not necessarily conscious or intentional, but if it reaches the point where it self-replicates then it becomes effectively a life form that starts to undergo Darwinian evolution and thus becomes very difficult to get rid of. The point is that all this is (potentially) just a straightforward consequence of the laws of physics, not some sci-fi super-villain going "Bwahahaha! Silly humans!" in the back of data center somewhere.
Yes, I follow your reasoning. I buy the existence of a subtle, self perpetuating public attitude. It may emergently coordinate to the degree it is indistinguishable from an independant living entity. Once it is named, it will be seen and observed everywhere, and blamed for all manner of evils. It's the boogieman, in reality: a manifestation of all our collective fears.
