David Friedman is the founder of Knox, a platform that helps customers buy their new home while ensuring their old house remains a reliable long-term investment. The company provides a product called "Keep Loan" which offers access to equity in one's home in the form of cash. They help customers find a mortgage for their new home and also sign a master and sublease for the old house to offset any income issues. Knox takes over the operations of the investment by finding tenants, property management, rent collection, and providing insurance. David believes that keeping one's old home is one of the best investing opportunities, and he has made it easy for customers to achieve it.