that's true, but plenty if people oppose building new apartments because, in general, the price will be high and they see this high prices and incorrectly conclude rents are rising when in reality, people move in, freeing up the less expensive places they were in before.

similarly they oppose because "gentrification" even though the evidence is that gentrification is net positive, even for those already living in the area. gentrification or not, people leave at the same rate. Those who stay see their income/wealth rise compared to the case of no-gentrification.