The comparison is renting versus buying the same place to live in. A common fallacy is assuming that the financial loss from renting is always larger than the financial loss from buying. I gave a concrete example of why your pure losses owning that place would be thousands of dollars higher than the pure losses from renting the same place. I didn't say being a landlord had a good return on investment, just that landlords can make a profit charging a rent below your cost to buy. As a consequence, if you invest the difference reasonably then your net worth can grow faster as a renter.

To put it another way, you could rent and save enough money to buy the house with cash before you'd be able to pay off your mortgage, ceteris paribus. You'd still have the house at the end.

Financial models that show you often come out ahead if you rent and put the difference in other investments have been done ad nauseam on the Internet, it doesn't need to be rehashed here.