The book written by Thomas J. Summary of The Millionaire Next Door Based on the review of The Millionaire Next Door by Thomas J. From the research, Stanley comes up with information that most of the millionaires are actually very careful in the way they spend their money, diet on not incurring too much debt, and strongly focus on building an investment wealth. What seemed like instant gratification did not lead to success; instead, the lessons of this book clarify that success can only be earned through commitment and perseverance followed by good planning.