Offering a PDF/Ebook with good content (one hopes) in exchange for joining an email list is Lead Generation 101. The book is a runup to a paid course he is offering.
"Pay $1 to access this file" OR Sign up for email sends confusing signals to users. To the author, book is not worth $1, it is worth one email list signup. To the user, the book's value is entirely relative. They can offer up their email (positive value perception), or they can leave the site (zero value perception).
"Pay $1 to access this file" OR Sign up for email sends confusing signals to users. To the author, book is not worth $1, it is worth one email list signup. To the user, the book's value is entirely relative. They can offer up their email (positive value perception), or they can leave the site (zero value perception).