This is mostly passive once you have it all set up, but it does take a lot of work at the beginning. Real estate investing also requires occasional maintenance. Currently, we invest in a couple of rental properties and earn about $500 profit from each per month. You can read more about my rental properties at Money Smart Life - Money Tips for a Better Life: How and Why I Became a Landlord.
If you watched the video, he goes into a discussion about shocks (about 8 minutes in) like bad investments but how they don't really matter as much if r (rate of return) is greater than g, the rate of economic growth. If r = 5% and g = 1%, then you can lose 80% (the difference) and still be ahead because the return on the remaining 20% has paced with economic growth.
Managerial accounting defines residual income in a corporate setting as the amount of leftover operating profit after all costs of capital used to generate the revenues have been paid. It is also considered the company's net operating income or the amount of profit that exceed its required rate of return. Residual income is normally used to assess the performance of a capital investment, team, department or business unit.