It's like the American opposition to pedestrianization of blocks. Pedestrianized blocks increase local business footfall and increase high margin economic activity.
New developments in your community increase value of your home, far better than restricting development.
The value of your home doesn't only depend on the fact that it's in a rich neighborhood with beautiful lawns, but the services and proximity to said services.
NYC is desireable, not because it's a big city... but because you can get services there. Take away the services - you take away all of the value proposition.
But then by same token we can also move to justifying other things, like not hiring people without CS degrees (I spent $xxx,xxx on my CS degree, I want to protect its value), only hiring other MBAs, only hiring people with prior experience in tech companies etc. – which can perpetuate and amplify inequality in opportunity among society.
At what point do we move from that to a more altruistic viewpoint? I am genuinely not sure.
Is the problem "losing value in my house" or "not realizing astronomical gains like my peers"? And if building much-needed housing does decrease your house's value then hey, maybe your house was overvalued at the price you paid and you made a bad 'investment'. Why punish everyone else and artificially strangle housing supply to cover your bad decision?
If it means try to use the heavy hand of the state to prevent others from living their best life, then you aren't protecting anything; you're violently stealing the future net worth of others and making it your own.
Markets also go downhill. If you really went all out with paying for it, you also need to hope that your employment will remain stable. People who are very comfortable with their job and predict no downsides are often the ones getting bitten when the market changes, as it always does.
The capitalistic attitude in a nutshell.