I think you answered your own question.
There were supposedly 9 vague clues in a poem the Fenn wrote that held the secret to where the chest of gold worth $1 million was hidden.
A real life treasure hunt in the Rocky Mountains somewhere.
Great story.
IIRC he said he wrote the book to get people to experience nature.
I believe he was vastly confused about his motive for writing the book and the motive of the people reading the book.
I doubt anyone who read this book and looked for the treasure enjoyed the experience. Nature was in fact their obstacle if not their enemy.
I'll bet most people who went out to search never stopped to appreciate nature. Most likely cursed nature.