Speaking as an author published by the major houses (Penguin Random House and Macmillan in the USA; Macmillan and Hachette in the UK) I'm not seeing my books hitting the ebook bestseller charts much -- but I'm not seeing my sales decline relative to where they were a few years ago, either. What seems to be happening is that the bestseller charts are being dogpiled by self-published titles on deep discount -- 99 cents to $2.99 seems to be typical. And the old joke "sell it at a loss, we'll make it up on volume" seems apposite at this point.