Why does the author have to write a book just to get your E-Mail? It's a transaction. Obviously as the consumer you would prefer having the upside without the downside. The same is true for the vendor.
We usually meet somewhere in the middle and call it a day.
GDPR would strongly disagree with you. Your personal information is not a currency and you should never be forced to part with in in exchange for goods and services. If you're worth dollars, you should be paying dollars.
According to GDPR you are. If your personal information is not required (from a technical standpoint) in order to use the service, you're not allowed to block access to the service if the user refuses to give you their personal information. That particular law is quite clear that requiring someone to give you their email address in exchange for digital goods that do not need your email address in order to function (like a PDF) is in violation.
GDPR may not apply depending on what jurisdiction this site falls under, but it sets the expectation for all digital goods anywhere in the world. If you're demanding someone's personal information as a currency rather than as a requirement, that is a scam.
If you want to make money, charge money. If you're not trying to make money, there's no need to require my email address in exchange for the product.
Because my email is free of spam right now and I'd prefer to keep it that way, especially without a promise my email is not going to get sold around in a mailing list.
I also shouldn't have to research around to see if a website author is the "type" to sell my email around, that's bad UX.
If the author didn't earn your trust prior to the exchange you won't convert to become his 100th customer and their content upgrade lost a potential customer. And if that's the case you're better off reading You've Got 8 Seconds.
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).
You have source to the google docs. If you want a pdf of the same book, what's the problem in giving your email? I scratch your back, you scratch my back.
