:::::Here is one of the reviews of the book: 

 :::::"Just when you think you know all there is to know about Jeffrey Dahmer one of the most notorious criminals of the past century—along comes My Friend Dahmer, which adds significantly to our understanding of this rare form of psychopathology." —Louis B. Schlesinger, PhD, Professor of Forensic Psychology, John Jay College of Criminal Justice  

 :::::While it's perfectly understandable that you personally don't find the book useful, others apparently do. Granted, I'm sure you're not alone, but in general, you seem to be in the minority. Out of 108 amazon reviews, 93 of them are 4 or 5/5 stars. Certainly readers are getting value from the book. –