I think they (correctly) feel that there is just so much demand that the middle class would quickly buy up available properties and they would be highly unlikely to hit prices affordable to the poor by market forces. This is simply because of the huge desirableness of living in CA and this weather. This would esp be true if the new units were in high enough quantity that the overall area would become safer.

And if the poor live in a rent controlled unit, they don't have any strong desire to live in a similar unit with more occupants on the same lot. They think more like an owner in that sense.

Supply & demand is a great concept but the supply will always be limited by a fixed quantity of land - whether its land in CA, land near transit, land with etc, etc. And some of them may feel the land they are on is hugely undervalued and unlikely to ever remain affordable.

I don't think your "correctly" parenthetical is apt — you are proposing that demand is infinite and therefore supply and demand does not apply. Clearly demand is not infinite because prices are finite. Also, if demand can eat up all of the supply, you are still supply-limited. That is supply and demand in action — you're imagining a scenario in which supply is still very constrained and claiming that prices will stay high. I agree! Supply needs to be less constrained than that to lower prices, which is kind of the general thrust of the YIMBYs.

Yes, rent control distorts supply and demand, leading to higher prices.

Land will eventually constrain, but at the moment SFBA has tons and tons of unused air that is kept off the market by zoning.

Your argument is not very clear to me. They may very correctly realize that when you take how large the demand is + how much land is up for sale + how much could possibly be built on it + which neighborhood they want to remain in... the chance the market will reduce those units to prices that affordable to them... the chances are very low. So its not really a surprise they become NIMBYs.

>will always be limited by a fixed quantity of land

Apartments exist in 3D space. A 2X height limit increase is as good as a 2X increase in available land.

Or maybe they feel that a lot of the tech boom is what caused the increase in population, and they don't trust those people to have their interests in mind when trying to create new housing.

Color that under "poor understanding of supply and demand."

Not really. I understand that Econ 101 gives a lot of people a mystical belief in the power of supply and demand. But real economies are not governed by one or two simple equations. If they were, building more and bigger freeways would solve traffic problems. It doesn't. [1]

As an example, look at how many Bay Area companies over the past decades have vigorously opened offices elsewhere, often moving whole slices of their companies to lower-cost areas. They are quite explicit this is due to rising costs. If costs didn't rise, or were rising more slowly, we would have even more demand for housing here. Or, put differently, reasonable increases in supply might not actually help current residents. But they could well increase pain for current residents: more traffic, more gentrification, more destruction of existing buildings and neighborhoods.

So it may be less "poor understanding of certain shallow econ dogmas" and "a strong understanding of what they stand to lose, and how often they've lost at the hands of affluent white people who are sure they know how to fix things". Consider James Baldwin, for example: https://www.youtube.com/watch?v=T8Abhj17kYU

[1] See, e.g.: https://www.wired.com/2014/06/wuwt-traffic-induced-demand/

Why? Why would a natural distrust of a group of people who has never seemed interested in their problems or wellbeing before be a "poor understanding of supply and demand"?

Your implication is that it is reasonable for this group to believe that NIMBYism will somehow prevent rents from rising, "because we don't trust tech workers," which is counterfactual. In this case, low- and high-pay renters' interests are almost entirely aligned.

My implication had nothing to do with NIMBYism. Just that they don't trust the tech workers to have their interests at heart.

Its entirely reasonable and possible to believe that neither group will promote an outcome that will help those people.