Some nations that are experiencing low (or even negative) population growth (Japan, South Korea, etc.) are concerned about how that low population growth will affect the nation’s socio-economic balance in the future. Elderly/retired people are not as productive, yet they still consume goods and services. Sufficient younger population would be required to produce food, provide medical care, repair machinery, etc. Without that younger population, the structure will begin to collapse–if you have 20% less people producing food, then people are going to start to go hungry.
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