Ah, that is your fundamental misunderstanding in all this. You seem to be under the impression that when people talk about an illusion of consciousness, they are referring to its existence. This is not true. Consciousness is real, we have all experienced it ourselves, and observed it in others. The tricky part with defining consciousness is not an issue of whether or not it is real, but an issue of boundaries. The "self" is like pornography, I know it when I see it, but it is impossible to decide on a clear border between objects and systems that have a "self" and those that do not.
The illusion is not that consciousness is not real, it is that it is continuous. Continuity is the illusion. The "self" goes away when the brain isn't functioning. It is constantly changing, disappearing, reappearing, and being rebuilt from scratch. It can be affected by physical effects from trauma, drugs, and even quantum effects. If you take the time to study phenomena such as schizophrenia, amnesia, and even phantom limbs, you will come to realize that brain is generating consciousness, and strange things can happen as it does.
To use an analogy that has been brought up before, consciousness is a process, much like running. It is, at its heart, a verb. To be or not to be, that is what consciousness is. Running happens in fits and starts as the legs move and the world flies by. It isn't the same running it was when the runner was a youth. It isn't the same running when one is pursuing a bus, celebrating spring, or escaping from a bear. Running can be fluid and precise, or jerky and disorganized. This is exactly the same as consciousness.
Once you come to terms with the fact that there really is no single, continuous "you", it will make the matter quite simple.
