How did you derive $160/month? 

Unless there are tons of Bear Sterns & Lehman's hiding in the shadows with derivatives and subprime mortgage packages to drop on our heads?

He taught the principals of leverage, both with money and multi-units and for that I can only assume the posters are financially maybe a) unaware of the value and haven't purchased his materials, or b) just naysayers because of all of the people who came after, or c) didn't have perspective on what value they might derive from the information kit.I for one believe the information was spot on, and perhaps even too difficult for most to comprehend and put into play, because it was outside the box thinking and truely is hard to pull off with the square-peg round hole RE agents, sellers and financial institutions that we label conventional."

I recently took very early retirement from working on Wall St. in NYC and I have a master's degree in FE so I am very much tune into the financial markets (equity, FI, derivatives, etc). 

@Wade KulesaI believe Dave Ramsey's 10 year number is derived from the common real estate cycle, as 10 years is the time to complete a real estate cycle. 

Securities and derivative trading not so much but more so since the advent of online forums and platforms. 

@Daniel LambertThe more units a property has the more it’s value will be derived from the income it produces.

This is not even considering the tax benefits nor the income derived from that asset over time.  

For a SFR, you are  using a variety of data sources to get the comps for an area (such as market price per sqft) but with a multifamily, you are not necessarily looking at price per sqft  or "like" properties per se, rather you initially have to determine the rental price & cash flow per unit from which you can then work backwards to ascertain or derive value.Also, unless you have a property under contract, the opposite of attention is what you are typically looking for in regards any deal so you may want to learn as much about ARVs as you can -- fast!

Our economies, financial instruments, accounting, market manipulation, crony capitalism, derivates, currency printing and delinking from gold standard leave our economy extremely complicated and fragile compared to 1929 when things were not as complicated.