In 'The Business of the 21st Century,' Robert T. Kiyosaki explains why you need to build your own business and which business is best. He argues that the old model of 'go to school, get a good job, and work hard' is obsolete. Kiyosaki makes a compelling case for network marketing as a revolutionary way to achieve wealth, not just by generating income, but by building assets. The book focuses on the importance of financial education and personal development, presenting a low-risk, low-capital path to building a business that can provide passive income and true financial freedom for anyone willing to learn and grow.