> bragging about selling your product by lying about what it can can do

Is there a billionaire past or present who didn't use this strategy?

(general perspective here, not specific of the exact case). It could be that _no_ book will be sufficient for that outcome. Because a book might not be the right tool. One might need to practice, get out there and actually do things. If so, it can be ethical to sell that it is a part of getting to the outcome wanted. Especially if one provides tips&tricks for the beyond-the-book part. Those kinds of things will be be great candidates for content marketing, or even small giveaways (commoditize your compliment), or partnering to offer the other parts of the package.

“What can it do?” if we are talking ceilings, then yes the book has successfully helped coders become contributors. I have several readers who got maintainer status on libraries after reading the book.

Now, is it guaranteed to do that for everyone? No.

If you view my marketing page, I’m curious what your thoughts and how it could be better.

I want to sell the upside but not over sell it. If you buy the book and never open it, it won’t help get any little green squares on GitHub.

That's far from lying. The book needs the reader engagement to be effective.