It took her 12 years to write a book! That’s not a successful author, that’s a hobbyist.
Look at an actual successful author like Nora Roberts. Since the start of 2012 she’s published 57 books!
And before you say “there’s no way those 57 books are as good as the one book which took 12 years to write” let’s look at reviews on Goodreads:
The Actual Star by Monica Byrne (2704 ratings for a 3.88 average rating).
Private Scandals (2012) by Nora Roberts (10151 ratings for a 4.01 average rating).
And that’s just one random book I picked by her. Many of them are way more popular than that (hundreds of thousands of ratings on Goodreads).
The point is: if you want to make money as an author (of books, video games, YouTube videos) you can’t ignore your own productivity. Taking 12 years to write a 624 page book is extremely unproductive! That’s 4383 days (including leap years) to write 624 pages for an average of 1 page per week. A part time newspaper columnist writes several times that output and probably spends no more than an hour or two working on it.
Edit: Just a side note. Lord of the Rings also took 12 years to write. However Tolkien was a full time professor at Oxford during that entire time.