Real estate's "gross rent multiplier" is Wall Street's "sales to revenue",  "cap rate" is roughly "P/E ratio".When evaluating markets and investments I tend to start with GRM (or lazily the 1% rule), then attempt to return a cap rate based on assumptions about costs, then I work my way to multiple years of projections (assumptions about inflation, amortization, tax benefits, etc), and if I am partnering with one of my smart friends I have to pull up an IRR (internal rate of return).I also look at regional employment levels, median income to rent ratio in the zip code etc. 

However I would sell these units as $500-550/month rent will never be sustainable.

We are all confused about what role a private lender plays, so here is a quick and dirty explanation.Unlike prime lenders (ex. big national and regional banks like Chase) that underwrite both the borrower's ability to repay the loan and the collateral (ex. real estate), private lenders make lending decisions based on the collateral. 

If curious, here are the last two: Jan 2023: Multifamily Real Estate is At Risk of CrashingFeb 2024: Multifamily is at High Risk of Continuing It's Historic CrashI think that the title for my 2025 analysis (likely Jan/Feb publication will be something more like:Multifamily is Finally Going to Hit Rock Bottom in Q2/Q3 2025 - Get Ready to Buy a LOT of itAs usual, I like to publish my draft thoughts here to get input from key players in the space and these forums, especially folks like @Brian Burke, to see if I am missing any high level areas, before I get into the weeds and look at the data more deeply and regionally. 

I guess it's all regional and depends on which month in 2021. 

I have an option in a 35 acre parcel that I am flipping to one of the major regionals here and its part of a 700 lot project the off sites are about 25 million.

.- Books:  We have a mix of books including some local area/regional stuff, some fiction, and kids books.- Kids Toys:  We advertise to families and have another 2xKallax cubes full of toys that won't break and are tolerant of missing pieces, but are easy enough to cleanup:  lincoln logs, blocks, hard animals, stuff like that.   

You could grow a portfolio but will it be sustainable?

Otherwise, his rental portfolio is sufficient to sustain him.

Most who try to replace their W2 income invest in less sustainable investment methods: investing in lower tier neighborhoods that cash flow well in spreadsheets or flipping homes.