Temporary dips in population have happened cyclically throughout history, and they have very real perks for those living through it.

Today, these population dips are forced upon us via onslaught of environmental poisons, demonization of marriage/family, forcing of LGBT/transgenderism/genital-mutilation on children, etc.

The resulting fertility collapse is then used as a pretext for infinity immigration, to ensure you get the worst of all worlds.