My subjective experience of reality is the only thing I have direct knowledge of. Everything else I must doubt. If you think about it, I am sure you will come to the same conclusion.
My paycheck says that I am a scientific researcher, and I have a deep appreciation for science. It provides me with models that go all the way from the subatomic world to societies, that expose regularities in reality, that allow me to understand how many things fit together, and to make predictions. But these are the things that are "just words" or, better yet, symbols. My conscious experience is the thing that I DO KNOW. Maybe it's all a dream. Maybe I'm a brain in a jar. Maybe I was created one nanosecond ago, and I am just a random fluctuation in some process and all of my memories are part of that.
And yet, and yet, the most fundamental phenomena of them all, the thing that I have experience of, is not predicted by any of the scientific models. There is no reason why a bunch of atoms should "become conscious" once their interactions are complex enough. There is no way to build a scientific instrument that measures consciousness. Sure, you can build a scientific instrument that detects brain states that we assume to be correlated with consciousness, but this is just crude analogy. Firstly we can never be sure, and secondly we don't know where the boundaries of the phenomenon are. Is a star conscious? Is the universe? Are the individual cells in your body? How do you know? How could you tell?
That is the mystery. I find that the people who deny the mystery have something equivalent to a religious belief, and that they are not necessarily aware of it . Believing that matter -> ??? -> consciousness is not so different from believing in creationism. A comforting story that makes reality seem intelligible, but that has no basis other than one's wishful thinking and group think. It certainly has nothing to do with science or rationality, at least so far.