it’s absorbed through osmosis by people living in capitalism and being surrounded by bourgeois media of all types .that and not being taught to think critically or creatively about anything. so people think population increase = more people within their personal space and possibly taking their resources.
the main referent is immigration and you know how that 's spoken about. unfortunately people would rather imagine themselves being a little fascist than imagine themselves challenging their hoarding employer / landlord / utility company / etc
it’s really easy when you imagine every delicate and bespoke part is a disposable piece of plastic designed to be interchangeable and taken apart and put back together in different arrangements then thrown in a box and stamped on by kids and pets and then to start again with nothing lost. nothing could go wrong with that analogy.