This book is basically a compilation of different famous investors and their advisory perspectives, and provides very little insight from the authors themselves. There are numerous contradicting advice. One wizard will be a proponent of diversification, others aren’t and then sums up to “just enough”, but all the points made are esoteric and abstract, subject to various interpretations depending on the perspective.
Ultimately the common message throughout the book is summarised as “listen only to yourself, work hard and put in the hours, make your own judgement, start early and be prepared to go the long run.”
Don’t waste your time.