But you're making a huge logical jump to say that building housing could magically slaughter my house value and that I'd be underwater because of it.
I'm worried about being underwater because of a recession or cyclical trends or tech jobs wholesale abandoning the area, or any number of things.
The LAST thing I worry about is housing being built so fast that it'll tank the value of my house. It simply won't. If there's enough continued demand for housing, by all means, build, build, build. It means neighborhoods will get more vibrant. I see no scenario where building will tank my house value (short of building and THEN a recession).
I don't think people worry about growth hurting their home value. I agree with others here that they worry about the impact on what THEY value in their neighborhood, but most people aren't looking to sell their primary residence so a temporary slowdown in the growth rate of the equity is simply not on their radar as an important matter.
If you bought recently, you probably had some sense that the market was a bit out of whack, but may have decided it was the right decision for other reasons. That doesn't make most people any less concerned about the future value of their house, particularly if they know they are not buying into their "Forever Home" and will one day need to sell and move elsewhere.
If you bought 20 years ago, even if a fire burnt down your house, it's likely that the land alone would give you a healthy profit. If you bought 2 years ago, a significant downturn in the market could leave you underwater.
Few people plan to sell their home shortly after buying it, but a market downturn could leave you without a job and you can't afford to move elsewhere for a job if you can't afford to take a loss by selling your house for less than your mortgage.
Given the amount of money at stake for said buyers, I can't say I entirely blame them for voting in their financial interests when the alternative might be a very bleak financial outlook, a decent chance of increased crime, traffic, etc.
It simply isn't a black and white issue.