Question

Good evening!
There are materialists who argue (for example, Daniel Dennett) that consciousness is an illusion, and not merely an emergent phenomenon. I don’t want to discuss the claim itself, which for now I’ll assume is utter nonsense (since there seems to be a logical contradiction in it—who exactly is being deluded? And the “I” is also the only experience whose existence we know and feel directly, without mediation). Rather, my question is: how can it be understood that educated people, and even philosophers, think this way? Are they not aware of their own existence?
Thank you very much!