You’re creating content that will sell for the rest of your life.
Not for a week, not for a month, not for a year, not even for a decade.
Your whole life, this stuff’s going to be selling, and you’ve got cycles when you can bring these series back so you’ll always be able to make money.
Bonus: How to Write a Query Letter
The Four Ingredients of a Query Letter, With Examples – or – How To Not Mess Up Your Chance at Traditional Publishing.