So let's put this in a family perspective. A family of five, the breadwinners are just getting by, but they decide to add a foster child. Maybe the foster child doesn't get first dibs on things, but the other children might not appreciate the new situation where things could be spread more thinly in an already tenuous situation.

It could be competition for jobs, ability to find affordable housing, decent schools, preservation of culture (let's remember the anti gentrification movement whose main complaints are loss of culture as well as displacement/loss of neighborhood character).