I am definitely not saying that it’s impossible to lose money renting. But if you can’t charge enough rent to cover your costs, then eventually you sell and go

I am definitely not saying that it’s impossible to lose money renting. But if you can’t charge enough rent to cover your costs, then eventually you sell and go buy a unit somewhere else that is profitable, or stop renting entirely, or declare bankruptcy, or.... This puts downward pressure on real estate prices in areas which are unprofitable by increasing inventory and decreasing investor demand for rental property. Market equilibrium will tend to drive prices to the point where units can be profitably rented, and rent will be higher in areas that are depreciating rather than appreciating. This is not a law in the sense of a inviolable law of physics, but I believe it is generally accepted macroeconomic theory.