I think, in many places, landlords aim to break even with rent covering house expenses and interest on borrowing. The profit comes from capital gains. This works especially "well" when you keep buying places because with rent covering the interest you need very little capital so you can keep buying creating a demand that raises house prices that gives you your profit.

This works great until people are priced out of the market dropping house prices a bit and then you've just got a lot of debt and houses worth less, you go bankrupt and someone _really_ wealthy pick up all your houses at a discount.

You can at least hope that the really wealthy guy didn't get that way selling a "get rich in the property market" book.