While you´re busy trying to theorise about how Lucid Dreams can´t exist, I<ll go ahead and have one anywayz.

I think you´ve become a little stuck in theorising so that you forgot that it´s simply not important for deciding wether Lucid Dreaming is real: If I have a Dream in which I suddenly realise that my surrounding enviroment and situation is all a dream, and from that moment on I gain enough consciousness to act/interact in that dream according to my own free will: Then I had a lucid dream. There are several levels of lucidity that´s when you´ve allready made it to the bottom of the "Lucid Scale".

Now you can bring all the scientific evidence in the world to persuade me to believe that what I just awoke from didn´t happen, but that just seems silly to me.
Seems just as silly as you looking at the Road, watching a bright Yellow, Green and Red van drive out of sight and then me telling you that that which you just saw wasn't there.