Selling books is so difficult because you don't know where your fans are. Because they're not aware that you exist yet.
Breaching the gap between author and potential fan is hard to do when you don't know how.
Times have changed, but that's a good thing. It means we can shift perspective. It means that we can find fans if we know where to look.
So where are your fans? How do you let them know you exist?
They're in the cracks and crevices. They listen to podcasts, read blog posts, watch videos. They follow their favorite authors on social media. They're subscribed to email lists like Bookbub, Book Gorilla, and Freebooksy. They may enjoy fanfics or follow authors on Wattpad.
There are countless ways to present your work, to get noticed. Some will be worth your time. Some won't.
What really matters is the connection between author and reader. Once the connection is made, selling your book is much easier.