Being a landlord has costs, but I'm not sure what your point is. Renting property is clearly profitable, or it wouldn't be so common.
A lot of the expenses happen when you switch tenants. In between tenants, before the new tenant arrive, the carpet may have to be replaced, the house may have to be repainted, various other maintenance jobs that are deffered must happen.
Being a landlord has costs, but I'm not sure what your point is. Renting property is clearly profitable, or it wouldn't be so common.