[Elepsis]

You are starting from the inexplicable premise that these properties he rents out were somehow ill-gotten, and not the direct consequence of him saving significant amounts of his income while he worked a totally normal job and investing them intelligently in property.

And of course landlords (since you're obviously using rentier as a pejorative) DO provide a valuable service: housing to people who either value the flexibility of renting or don't have the finances to buy housing where they live.

Your apparent disagreement with the entire system of rental property around the world is certainly principled, but singling out Mr. Money Mustache as some kind of hypocrite for earning money off his investments is absurd on its face. Are you also opposed to people buying dividend-issuing stocks?