Earlier quoted context omitted.
Yeah, it has a lot to do with selfishness. More housing means more people means you have a lower property value for you home in the area. Further, it means your vote becomes less powerful as the poors that live in the high rise have the same voting power as you do in your single family home.
I think it has a lot to do with people believing what you just said. Which is, of course, utter nonsense! If a neighborhood suddenly gets rezoned for 20-story mixed-use development, an existing house will be devalued, but an existing lot will likely gain more then enough value to compensate.
That doesn't change the loss of voting power. Further, value to who? I agree a 20 story high-rise has more value than a single-family home, but how does that help the single-family homeowner or the homeowners that live around the lot that gets rezoned?
That's the problem. The existing homes and their owners seem mostly downsides to rezoning even though the city as a whole would benefit greatly from them.