Well, I wouldn't use the word "bullshit" to describe the book.
Reading (most of) the book caused me to change my priorities from basically "I don't care about how much sleep I get" to "getting enough sleep is an important priority for me". Presumably you would agree that that is a positive effect.
Sure, I have nothing against getting enough sleep but the book's first 10 pages contain so much misinformation and given that Walker outright falsifies the data in the book (https://guzey.com/books/why-we-sleep/#appendix-what-do-you-d...) I would struggle to call it anything other than bullshit.
Reading (most of) the book caused me to change my priorities from basically "I don't care about how much sleep I get" to "getting enough sleep is an important priority for me". Presumably you would agree that that is a positive effect.