I build FIRE calculators, and the difference between "retire at 55" and "retire at 65" is almost always housing. A $2K/month difference in housing costs (say, HCOL city vs. LCOL area) means you need ~$600K more in your retirement portfolio at a 4% withdrawal rate. That's 5-8 extra years of saving for most people.

The math is cold: if your annual spending drops by $24K, your FIRE number drops by $600K ($24K / 0.04). Building more housing supply doesn't just help renters — it directly shortens the timeline to financial independence for anyone planning their retirement around current rent prices.

From the Zumper report. 22% gain on SF 2B is just insane to me.

Does that mean the "surge in supply" is really a surge in permits?

San Diego County includes La Jolla and points further north, as well as El Cajon and Jamul and all sorts of suburbs. It's a huge area with many disparate neighborhoods (and even 4 microclimates.)

The City of San Diego includes very undesirable neighborhoods such as most of Downtown. There are a lot of places where normal people would have a terrible time, despite still being expensive. But there are also many different parts of the County which are "bad neighborhoods" and upscale places and ethnic enclaves, etc.

Honestly, I was a little surprised that these articles are specifically referring to only the City in terms of housing supply. The vast majority of San Diegans don't even live in the city. I mean, it's not as pathological as Los Angeles and its county, but it's an important distinction that's often lost on out-of-towners.

https://x.com/HotAisle/status/2046792071521157600 (taken tonight)

More housing is always a good thing though

I'm not sure where the "19 of 20" comes from because I grabbed the data from the report into a Google Sheet and sorted and it's not #19 by 1br Y/Y, 2br Y/Y or average rent. What it shows is 1br -5.6% and 2br -7.5% Y/Y. LA was -3.6%/-2.5%.

It's hard to find a comparable city to this because there aren't actually a lot of coastal cities in the US that aren't mega-cities (eg Boston, New York, Miami, Houston).

It seems like San Diego built ~4000 new housing units in 2025 with a population of ~1.4M. For comparison, Miami seems to have added ~18,000 but it's population also exceeds 6M so is that a fair comparison?

My point here is that the direct evidence linking building new housing units to changes in rent is weak.

Not that I'm opposed to building by any means but simply blindly building more units is by itself not an answer. It depends on what you build, where you build it and whether you allow effective or actual cartels to monopolize that supply.

Take Manhattan as an extreme example. There has been a ton of building along so-called Billionaire's Row and also some pockets in the Financial District, West Chelsea, the UES and so on. A lot of this stock is the so-called ultra-luxury market. Prices for some of these new units are now exceeding $7000/sq ft.

That is going to help absolutely nobody. Ultra-wealthy non-residents will park money there and that's it. This blind assumption that it will eventually become prole housing is ludicrous.

Housing should primarily be for shelter, not a speculative asset or investment vehicle to get wealthy by denying someone else shelter.

[1]: https://www.zumper.com/rent-research/national-rent-report

[2]: https://www.zumper.com/blog/our-methodology-empowering-the-r...

1) Rent-Fixing: This is widespread across the country and the actual reason why inventory increases often (commonly) do not lower prices. There are multiple tactics landlords have used to ratchet up rates without ever letting them drop. These include lease concessions that don't affect the base rent in lieu of rate drops in step with lowered demand, warehousing that artificially limits accessible supply even when new, physical units are hitting the market, and algorithmic price-fixing had allowed landlords within a region to stay in lock step without breaking rank lower. When landlords are able to use such tactics with impunity, they absolutely do warp supply-demand dynamics and allow rent rates to stay high even in the face of expanding actual inventory. For rents to decline, you have to break large landlords' ability to set their price.

2) Builder Subsidies: "Just build more and prices will drop," ignores that the incentive structures municipalities use to draw developers are an additional burden on residents. These for-profit corporations then seek to make a profit on their investment, leading to no direct meaningful inventory increase in the affordable unit range. Worse, developers often target existing affordable units for their redevelopment, destroying the very units that the new inventory is supposed to ultimately reduce demand for. In order for "build more" to drive down rents, it can't be done the way it has been, which mostly ends up being a giveaway to developers at the expense of the tax base and displaced renters.

San Diego is a special case where it seems that the expanding inventory has been driven not by corporate developers, but by the construction of ADUs, which are built by homeowners out-of-pocket, are not tax-subsidized and, in fact, increase the taxable value of property. In this way, they work almost counter to traditional development, and these factors combine with their being created and operated outside of the control of corporate landlords means that they represent new and meaningful competition to those landlords. Thus, efficiencies are sought and prices drop.

Encourage ADUs. Avoid subsidizing large developers and corporate landlords. If there is the political will, get the government directly involved in constructing subsidized owner-occupied, human-scale housing, as in Singapore and the pre-Thatcher UK. Relax zoning and build out public transit and car-free infrastructure in order to reduce the accessibility premium, as in Japan. That is how "build more" actually can work to lower rates.

People in the year 1500 could pretty reliably tell you that a rock would fall down if you released it from a height. People would also tell you that if you threw it up and away, it would go up in an arc and fall down.

The innovation that Newtown and friends brought about was they made quantitative predictions about the rate at which the rock would fall down, or the arc it would follow - both to pretty high level of accuracy.

The point is that, of course, building more houses has a tendency to reduce rents. The question is whether reduction is -0.1% or -10% or there is an increase of +5% because some other factor was more dominant. It would be very hard for policy makers to argue against building more housing, if there was a quantitative model that predicted exact numbers for how much rent fell down given all relevant factors, and this model had been validated over and over again by prediction (not retrodiction). Rather than "rock fall down if you drop it" model that everyone keeps quoting.