Most homeowners just don't want things to change.
Housing prices only come up when people try to engage in bad faith gymnastics about how actually they only paid 200K for their two million dollar house so they're totally just ordinary middle class people with middle class concerns.
By describing it a "fear of change" you are assuming (I think) that the change is always good for everyone, people just "fear it" irrationally.
The reality is that most people choose where to buy a house based on some criteria of what they like and the lifestyle they want. Whatever it may be for them, but nearly everyone puts a huge amount of effort in considering what they want from a neighborhood and then try to find a matching location to buy a house.
If you come in and completely change the nature of the neighborhood, in a way that makes it incompatible with why they chose it, of course they'll hate it. You would too if it happens to you. Every human would, basic human nature.
Think, or feel? Rationally, most people might realize that over the decades places will change.
Emotionally, if you put it a huge amount of effort and more money than you've ever spent (or ever will) on anything else and then someone comes in and changes everything about it that you originally loved, you will hate it. Basic undeniable human nature.
It's much harder to act like the good guy when you're talking about turning a quiet neighborhood into a much denser neighborhood where the kids can't walk to school anymore because there are too many cars.
I never understand why people are so eager to turn a neighborhood they don't live in into something else rather than move to any of the multitude of neighborhoods that are already like that.
Imagine if someone wanted to change all the streets in your neighborhood to only accomodate bicycles but you own a home in the center of the city and commute 20 miles to a town in another county for work.
Unfortunately that means they can play both cards, they can benefit from scarcity while pretending to be anti-gentrification. And they can claim any pro-housing group is actually “pro scary capitalist developer”.