> Free markets for housing are likely to settle into an "optimum" where some percentage of people cannot afford housing at all, because while construction/rental of housing for them would net a return, it's not worth the opportunity cost

You provide no basis for the idea that the returns on housing have to drop below the point at which its financially viable to build before housing becomes affordable. You just say "because" then restate your premise.

> Markets don't optimize for "everyone gets some", yet that's precisely what you need for housing.

Just because markets don't optimize for it, doesn't mean it doesn't achieve it.

> You'll always need the government to come in at some point to provide for those left behind by the free market.

Disagree.