Ideally a growing city would build enough new housing to accommodate all it's citizens. If there isn't enough built, developers will spend their square footage on the highest paying people first. And generally the rich are better at effective NIMBYism than poor people, meaning that new development aimed at rich people gets pushed into poor neighborhoods, which does actually suck for poor people. The best solution is not to panic about the second order effects, but to try to get to the root of the problem and build more housing, and do it everywhere.