The author of the $30 dollar novel published by a traditional publisher would be receiving about 10% of the sales price - $3.00. An independent author who sells through Amazon would receive 30% - 70% of the sales price on an ebook.
However, independent authors (ordinarily) sell very few books.
For me, no, it isn't profitable. It might one day be, but the satisfaction of having written and having been read outweighs the economics for me. As long as someone's read what I've written - even one person - then I really don't care.