Of course people build to make money. Don't you go to work to make money too? Who's going to work or build something if they can't make money? There's nothing immoral about that. No one works for nothing. Do wedding photographers work for free? They're business people. Only socialists think like that. Get over it. When someone starts a business, they think there's a need for it and they'll get customers. If there's a market for low cost rental housing, it will be built.
That's the problem right there...if there is a market...in other words if they can make a bunch of money, low cost housing will be built. But if there is something better to build, that low cost housing and the potential tenants will be out of luck...out on the streets...rising crime rates...building yet more prisons...and in the end costing the government way more money than if they just built low cost housing in the first place.
Some things like a place to hang your hat, your health, food etc...are not a luxury, but a necessity and its government, in fact the people like you Alan, that should ensure this necessity of life is available to all. It is not something that the rich should get richer from nor neglect because they can't make a buck from it. It's just basic good humanity and I'm glad that there are parts of this world that don't live and die by the almighty buck.