He forgot to factor in the ~$250K cash downpayment to buy that $1MM mortgage. The opportunity cost on that over the next 30 years has to be added in. At 7% annual return (which you can get from Vanguard mutual funds) that 250K is worth almost $2MM in 30 years. Sure, rents will rise over time, but it's probably closer to a wash when you figure the insane downpayments you have to make.