The MLM scammers may have used the book for their own purposes, but that shouldn't detract from the book's value. The book was published in 1937, during the great depression, and is based on study of some of the most successful businessmen of all time like Rockefeller and Carnegie.

The bottom line of the book is that the "secret", at least as I understand it, is perseverance and hard work, which is exactly the opposite of MLM get rich quick schemes.

It's not a how to book, it's more of a motivational book.