This may skew the number-of-titles stats, but it does nothing to lessen the fact that total number of Kindle sales exceeds hardcovers. While there are of course exceptions, the sad truth is that most self-published material is garbage and most self-pub titles sell no more than dozens of copies, no matter the format.
I'd say the most obscure title can sell a couple hundred, even if its just friends and family. If tens of thousands of titles sell several hundred each it all adds up.
If this were true across the board an author like Stephen King (for example only, I didn't ask him) would say his sales last month were more than half e-books. Publishers are very stingy with their sales numbers however individual bestselling authors who I have in fact asked, report e-book sales are presently somewhere between 1% and 3% of print sales. So something is out of whack here.