It's difficult to assess what the point of this book is. Though detailed, it lacks any central vehicle or storytelling device to either give the reader a moral lesson, or offer ruminations on how/why the cartel situation and propensity towards violence has become so destructive in the 21st Century.
My assumption is that the author leaves much out of his book - likely for good reason. However, as written, the text leads a reader to assume that the author fell into a life of violent crime almost without cause, and certainly by choice. There doesn't appear to be any prime motivation or influence beyond a desire for street fame - the author claims to have a reasonably stable and balanced if poorer household, and developed a mixture of depression, nihilism, and a taste for drugs at a young age.
So, why a life of crime? The book leaves this question unaddressed, and instead focuses upon decades of partying, drugs, sex, and various criminal acts ranging from petty larceny to rampage murder. At the close of each chapter, I kept asking myself (increasingly angry)....why?? I was unable to discern any clear answer.
I am not sure what the sicario author is 'confessing' to per the book's title, nor do I understand what the ultimate point of the book is. If all it was intended to be is a list of misdeeds and past regrets, then mission accomplished. However, the author passed upon an incredibly valuable and needed opportunity to teach precisely how and why they ended up at such a destructive end, and more importantly what some steps may include to keep at-risk youth from a similar fate.