It is self-evident in that it follows logically without any sort of assumptions whatsoever, merely by examining the concept of free will. Perhaps you mean something different.
The concept and the thing conceived of are two different things. Sunrises did not cease when heliocentrism began. That someone conceptualises something in a way that can easily be knocked down does not mean that there was nothing there. Dennett makes this point in his review.
I've raised arguments for philosophical scepticism before, which have mostly been argued against in a Popper-esque manner of arguing that even if we don't know anything with certainty, we can have legitimate knowledge on probabilities.
The problem with this, however, is how you answer a sceptic about the notion of probability having a correlation with reality. Probability depends upon axioms of probability- how are said axioms to be justified? It can't be by definition, or it has no correlation to reality.