The Life-Cycle Hypothesis, Consumption Smoothing And Saving For Retirement : Planet Money Summer School Even if you don't own stocks, there are a lot of reasons to care about investing. We meet some of the folks left out of the stock market who deploy sophisticated economic thinking, even creating their own alternate financial systems. Our professors help us understand how consumption smoothing and life-cycle theory apply to personal finance. And we meet the creator of the 401(k). | Watch this Tik Tok to learn more. | Subscribe to our weekly newsletter here.