There used to be only traditional publishing houses. Authors would write a book and submit it to a publishing house (sometimes all of them) then cross their fingers, pray, and wait only to be struck down. There were a lot of good books that never made it to the reader.
Today there are so many avenues for an author. An author can do all of the work themselves, pay someone else to do the work, or try for the traditional publishing. Everyone has their own idea about what they want their book to accomplish so their avenues are just as varied.
One realization is that, with the new ways to publish, there are as many or more bad books on the shelves as there were good books missing from the shelves when traditional publishing was the only option.
If you do write a book, keep in mind your purpose. Is it to get your story out there, help others, or to get rich quick? If it’s the latter you may be heading toward a huge disappointment. There are some that do make it. Fifty Shades of Grey was self-published. But, how many more published books went to print that week… that day?
If it’s to get your story out there then do it for that purpose and that mindset. Write it from the heart and don’t worry about the fame or fortune. If it comes, it comes but if not you’ve still reached your goal.
If your book is to help others there’s no better example than Dr. Richard Dew. His books have helped a lot of people and he’s become a hero to so many with his book: Rachel’s Cry (a book of poetry), Tunnel of Light (working through loss and grief), and Medicine with a Human Touch (improvements in patient care). Have these writings made him millions? No. The books have made him wealthy in so many other ways through changing lives. This was his goal so he has achieved his greatness through his devotion to helping others.
When writing your “great American novel” getting your head and your heart in the right place should be done before the first keystroke. This is what makes good writing.