One big source of apartments being too expensive to rent is investment companies swooping in to buy apartment buildings, hoping the _building itself_ will appreciate in value, so that they can then sell it later at a profit. In this model, it's actually against the owner's interest to rent apartments because renters inevitably cause damage that needs fixing, which cuts into the owner's bottom line and makes the building less resellable. So, the solution is to charge exorbitant, insane above market rents; a small number of fools with more money than sense will rent at that price, and that will help cover loan interest costs, etc. in the meantime. With enough starting capital, renting to a few tenants at very high prices is a much better investment than renting to many tenants at market rates. You just hope that the building appreciates by a large margin in the next X years while your few, wealthy tenants pay your interest, and then you can sell the whole building to the next investor.

Now, is this ethical? Abso-fucking-lutely not. Not only is it basically a bigger fool scam, it takes an extremely valuable and important commodity (housing) out of the market for no reason other than financial gain. I'm of the opinion that apartment buildings should be required to maintain 80% occupancy or risk having their apartments go rent controlled; if you aren't willing to rent at market rates in order to provide the service you claim to provide, you're taking housing away from people who need it, and you should be punished for it. Sure, you can argue that real estate is an investment and therefore these ghouls have the right to do this, but IMO becoming a landlord should come with the social responsibility to _increase_ housing supply and availability, not decrease it. If you're not willing to play by those rules you shouldn't be allowed to participate in the market.