For book/ebook authors, publishers, & self-publishers
The biggest challenge for most book authors is very simple: They don't believe in their books enough to spend some time every day marketing their books.
I so agree with you, John! That's what I keep telling authors.
I'd imagine the answer is fairly simple. Being noticed. The world is flooded with books. Quite often books by indie authors are of a higher standard than those pumped out by commercial publishers. It mostly comes down to marketing. If a book is pushed hard enough and enough money is spent then the you'll probably have a best seller. The actual quality of the writing will be secondary. Against all this you have the independent authors desperately trying to be seen and get some traction.