It happened to me the other way around when I was younger. I spent a lot of money on bullshit because I didn't know if I was going to die tomorrow and with hindsight that money spent didn't make me any happier.
No, this is not what the book is about.
People who waste money in bullshit aren't the target audience of the book.
This book is written for people who invested a lot of money over the life and should review their accumulation goals.
I believe especially people who focused since early professional life in the FIRE moviment , quite common in my generation, which many people live a very frugal life saving a lot