Why You Need to Be Invested in Businesses March 2, 2020 by Scott Wetzel This is a slide from John Bogle’s book The Little Book of Common Sense Investing. What this graph importantly depicts is that the stock market during the time period shown basically grew at the same growth rate as that of public companies. Public companies make and price the products that consumer’s purchase, and this graph shows why it’s important to be invested in stocks or the stock market for the long haul, so you keep up with the rising costs of inflation.