Elmer Wheeler famously said that people don’t buy quarter inch drills because they want quarter inch drills. They buy quarter inch drills because they want quarter inch holes.
They don’t want the thing, they want what the thing will do for them.
When you’re selling something, you have to sell the benefit of it.
“But wait,” you say. “I’m not a salesperson, I’m a writer—I’m an artist!” Yes, that’s true, but if you want to earn a living you’re also a salesperson.
People don’t buy books because they want books. They buy books because they want what the book will do for them. They want to learn, to be entertained or to escape.
What does your book do for your reader?