All this, plus you forgot taxes & insurance. Not even homeowners insurance, but liability insurance in case someone hurts themselves on your property. You need to cover times it's not occupied, pay for a property manager, any legal costs when a renter abandons the property and you need to instantly evict them, clean up costs between each tenant.

Building equity on a property backed by a mortgage is such a slow process that the only way to make profit (in my real estate market) is to eek out a thin margin every month and cross your fingers nothing breaks.