That’s the other thing: real estate is not a guaranteed investment. If you invest money in a house and its value goes down, I’m sorry, but that’s the risk you take. A home is not a guaranteed investment vehicle, despite that being the outcome when NIMBYs vote and craft policy to make it so.
Also, I don’t think people’s home values drop all that dramatically when new housing is built. We’ve been putting this off for decades, but we’ve also been artificially inflating housing prices. Maybe your tiny bungalow ISN’T actually worth $500,000. Maybe decades of bad local policy have ballooned the price of your house at the expense of others.
And even so, even if building housing makes your house decrease in value, that’s still not a good reason to prevent development. I care much more they cities are healthy and plentiful housing than I do about some Boomers who got lucky with when they bought into the real estate market.
The solution is actually remarkably simple: build more housing. We did it before; plenty of other countries with more sensible zoning laws do it. There aren’t enough places for people to live. We can either start killing people, or we can put up some walls. Personally, I’m a fan of buildings.
Edit: typos (phone)