The model described in the book does work. Spend less than you make, invest the excess in long term assets that have compounding interest rates above the inflation rate. It does produce millionaires. It also requires tremendous discipline over a long period of time. The math is relatively simple, the behavior is not.
While the millionaire described in the story had $8 million in assets, you will find almost no one "next door" with 10 to 100 million or a 1 billion. That level of wealth requires a return on investment that can't be achieved using the earn and save model. It usually requires creating/controlling an assets that can grow in value many orders of magnitude faster than the stock market (real estate, businesses, intellectual property).
While the millionaire described in the story had $8 million in assets, you will find almost no one "next door" with 10 to 100 million or a 1 billion. That level of wealth requires a return on investment that can't be achieved using the earn and save model. It usually requires creating/controlling an assets that can grow in value many orders of magnitude faster than the stock market (real estate, businesses, intellectual property).