I think more and more people are recognizing the advantages of having multiple sources of income, thanks to the Great Recession. It was a real wake-up call to many good workers who lost jobs not because of poor performance but due to restructuring and cost-savings. They never considered themselves to be vulnerable and they were. We do have multiple streams of income and a fully-funded emergency fund, which has helped my family weather the ups and down life has brought us, including job loss.

You’re right Ed, it does require capital to get income from a rental property. However, I started hustling when I was a teen, baby-sitting, teaching younger kids the piano, doing homework with middle schoolers, being a French and Spanish tutor, none of which requires an initial investment. As do pet sitting, housekeeping, lawn mowing, house painting, and many gigs around.
An obvious example is over exposure to bank stocks, which have been excellent investments for over a century.  Though a foundation of most portfolios, bank stocks do involve more risk at certain stages of the economic cycle than many realise.  Being less exposed to bank shares in the last few months could have preserved some capital.  So, a more diversified approach can help mitigate some of these risks.