Nelson Nash answers the question best in this excerpt from his book:

“The whole idea is to recapture the interest that one is paying to banks and finance companies for the major items that we need during a lifetime, such as automobiles, major appliances, education, homes, investment opportunities, business equipment, etc.

This book is not about investments of any kind. It is about how one finances the things of life, which can certainly include investments. It is not about rates of return. As time goes by interest rates are up and interest rates are down — but the process of banking goes on no matter what is happening. It is a well-known fact that banks make more money during times of low-interest rates than when rates are high.