I take the argument that from an economists view point negative population growth is a very bad thing indeed. But from an individuals point of view actually not. Because the economist only cares about total 'GDP' and is absolutely uninterested in quality of life. Because quality of life can't be monetized.

From an individuals point of view lower population means fix resources are spread less thinly. There is less competition for jobs so you can command a large share of the pie.