I get the concern for sure, but is it actually a risk that needs mitigation, or just a concern that needs better information?

I haven't conducted a comprehensive study, but my general sense is that the value of any given housing unit correlates fairly positively with density. An average sized single family house in the middle of a dense city is generally going to be worth way more than the same house located in an exurb. I'm sure there are counter examples, but I'd be willing to bet that for the most part, the denser the area, the more valuable the housing.

Basic supply and demand might suggest the value of your house would go down the more housing is built in your neighborhood, but that ignores that more housing might create even more demand because the increased population and density makes it a more desirable place to live. And if you own lower density housing from before all that growth, your house can demand a premium for people who want the benefits of density but are able to pay for more space for themselves.

Houses are for living, not to be your piggy bank.

But for decades, the US economy has sold SFH as just that. Every time I go to the bank, I get solicited by a bank employee to take out a HELOC.

I agree that's how it should be, but unfortunately buying a house is commonly understood to be a great investment strategy. And in this precarious economy with few safety nets, people clutch tightly to their home values. These people also have lots of power within HOAs (a strange and powerful quasi-government structure) and tends to be more influential in local politics.

As someone with progressive politics, I believe this is a huge problem.

I would mention that it may actually cause property values to go up for single family homeowners. Reason being a developer would have the ability to buy the whole property and build an apartment building.

Each apartment may cost less than the house that was there before, but the value of property together (land + apartment building + individual units) is sure to cost more than when only a single home was on it.

Condo owners, on the other hand, would see the value of their units decrease with the extra competing supply. This, of course, being one of the benefits of YIMBYism for everyone else (increases affordability).

Others, though, see increased higher density housing as more traffic, increased crowding in existing schools, and lowering property values. At least in the US, higher density housing in the surburbs is seen as a negative, even if there may be some benefits, however nebulous.

> I would mention that it may actually cause property values to go up for single family homeowners.

This is an exception more than a rule, and generally only for specific areas that might be gentrifying or for home owners in very old properties that might border a larger land area a developer might buy.

And then you always have holdouts which could spoil the deal, which leads to IMO one of the most evil government things there is in the US in modern times—eminent domain

Eminent domain is amazing. It should be used more often. The key is that the people whose property is being taken should be fairly compensated.

What’s “fair”? Who gets to chose that number? The developer? The government that stands to gain from larger tax revenue from the same property?

Sorry it’s a purely evil thing. Specifically designed to rid poor people of property to enrich the pockets of wealthier people. Hell, Donald Trump was the biggest cheerleader of its use in the ‘90s.

The problem is that zoning is so incredibly restricted, if any place becomes even vaguely developed in a modern mix use way, property prices go up like crazy.

If simply everything was getting developed, then the impact would be much more distributed.

There is also systematic bias and failure in the property assessment system. Strongtowns has been doing a lot of work on that.