According to the iPad Ibook/eBook forum, that does not seem the case, in fact they are suggesting that is is a lot cheaper and easier to provide eBooks therefore expanding your userbase. Here is a recent reply to the subject:

Several of my traditionally published author friends are also reluctant to make the shift, there does seem to be a strain of technophobia among some authors.
But as a self-published author, who doesn't have a lot of technical experience, I found it pretty easy to do.

However, the first hurdle is whether or not they have the rights to their books. If they do, then I would suggest several approaches.

First of all, you might send them links to JA Konrath's blog A Newbie's Guide to Publishing A Newbie's Guide to Publishing (specially his posts on how much money he has made since starting to put out ebooks.) Then I would recommend they look into Smashwords, with their free downloadable guides, which make it easy to format your electronic files into a variety of eformats. If an author goes the Smashwords premium route, eventually their books can be available in the Ibooks store. Finally uploading files to Kindle (which will also get you into Ibooks through Kindle Apps) is also easy with several guides available on how to do it. April Hamilton' Indie Author Guide was very helpful and a paper edition is due out in November.

Perhaps one of the most effective arguments is royalty rates. With Kindle, if you sell within certain guidelines your royalty rate is 70%, With Smashwords, your rate is 85% if you sell directly, and 45-60% if you sell through an affiliate like Ibooks. And, you don't have to mess with worrying about sales taxes, garage's full of books, returns, etc.

I have just published one novel so far, an historical mystery, Maids of Misfortune, which can be found in the ibooks store, but after 8 months I have sold over a thousand books, and at $2.99 price I am making nearly $600 a month.

I hope this helps.

M. Louisa Locke