The subcategory of NIMBY hate regarding overdevelopment of existing communities (as opposed to things like datacenters, multi-home owners concerned about investment, etc etc) is mostly hatred of the average citizen, which is not a great category of people to decide to hate. 90% of people would react the same ways in the same situations.

The obvious problem is that you can only develop a "desirable" area so much before you have fundamentally altered it. When there is a perception that the demand is driven in large part by people moving into the country, rather than by being born, that naturally engenders bitterness. When there is a perception that there are plenty of other areas available for development, which would then become desirable over time, but the developers want money and the government is focused on short-term goals, that further engenders bitterness. This is all very natural, and doesn't necessitate people to be unreasonably NIMBY to oppose it. Again, most people would.