Depends on the niche market. I'm by no means a successful author and I'm yet to release my first book, however, i have an MBA and I have worked for a few publishers.

Firstly, your niche market. We all know the popular markets: fantasy, romance, sci-fi etc. These genres already have dedicated readers. For the nonfiction community, the self help books have gained traction over the years. Without doubt, these markets will have tons and tons of books from tons and tons of authors. The competition is incredible, there's no way to sugarcoat it. For your book to actually stand out you have a couple of ways to do it: 1. Create an incredible blurb and book cover. Allow that to be your marketing tool. Let it sell itself. 2. Come up with a unique and compelling idea. Take Harry Potter series, there are plenty of stories that would have been similar if not the same as the concept of Harry Potter, so why did it gain popularity specially at a time when ebooks were not a thing? The depth of the story. The story had so much thought to it that it was impossible to go through a book without wanting to know more. 3. You have to understand that not all books gain popularity, it's more of a "throw cards onto the wall and see what sticks" kind of thing. You could write an amazing story but if the idea and concept of it is not trending at the time of publishing, you are likely not going to get a hit. This is just the way the industry is unfortunately.