Just by way of an alternate view, airports are/were built on what is now prime land - flat, stable, not prone to flooding - all the qualities sought out for a variety of other reasons too. Granted, people moved into the area knowing an airport was there, but there weren't many alternate choices, particularly in Sydney. The city has to expand somewhere. Saying "The airport was here first." doesn't work. The decision generally comes down to one of economics, with just a little politics, although many might think otherwise.
If you want to keep an airport, justify it. Many posters here are doing just what they are accusing the general public of doing - whining.