They are though. They objectively are impacted. Your new high-rise often does any/all of the following:
- change the elevation or the permeability of the ground (in the midwest, this means often dumping higher water levels into nearby properties, causing basements to flood that didn't before). In my home state, often 25 to 40% of a home's finished livable SQFT is in those basements)
- dumps lots of new vehicles and new traffic into the neighborhood (that the high-density housing isn't going to build parking for, in their obvious-lie greenwashing attempt to be 'eco-friendly')
- adds new retail on the ground floor, with more noise and more traffic (so that the business becomes viable)
- increase the costs of all insurance (automobile insurance, homeowners insurance, flood insurance, etc)
And of course, the big one:
- Dramatically increases the value of the property, immediately driving cost of living up for existing residents, in addition to increasing the housing costs for all residents (yes, even for pre-existing owner-occupants).
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You can argue that existing residents should just eat all of that, as like, "the cost of living in a society" or somesuch. Because your right, regular people didn't buy up that land too, to prevent the development ahead-of-time. And I get, new housing has to go somewhere, no one is against all new housing.
But you can't pretend these effects are "entirely intangible". New development, especially anything that "increases density" has lots of direct short-term real-world observable impacts, and very real costs, passed directly onto each other nearby resident. They aren't crazy to complain about all that, even if they aren't articulate enough to accurately name each effect individually, and instead label the whole thing "the character of the neighborhood" or similar.