In my view it is deluding oneself to be pleased about a falling shareprice when one already has a sizeable holding. Its rather like the way politicians of all parties put a positive spin on a bye election result despite the fact that that at least one of them have (usually) failed miserably.
I have a small holding and will not be buying more because I believe this to be a very speculative stock. Equally, as I bought these as a punt, I will stick with what I have unless there are signs of complete price collapse.