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Comment by socalgal2 | Hacker News Reader

This just seems obviously false. I'm sure their data shows something but come on, take a population of 5,000,000. Reduce it to 1. 1 person can not do all the things needed to run a society. They can barely do the stuff needed for 1. Specialization makes things possible. So then the question becomes, what number is too small.

Population of Seoul metro is 26 million people. It's suppose to drop by 2/3rds by 2060 (or worse). That's 1/3 less taxes, a 1/3 less transportation riders, 1/3rd less customers, etc....

https://www.youtube.com/watch?v=Ufmu1WD2TSk

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You are entirely right; but the conclusion they intend to argue for is that immigration supplements the declining population, still this is obviously just an attempt at giving authority to preconceived political beliefs.

>Population of Seoul metro is 26 million people. It's suppose to drop by 2/3rds by 2060 (or worse)

This doesn't make any sense at all. The median age of Seoul is 42, slightly younger than the national average. 2060 is in 35 years. If Seoul had zero births, zero immigration, most people in Seoul today will still be alive by 2060.

I feel like every time someone comes up with one of these predictions the numbers get more nonsensical.

Yes, "most people" will be. But they lose 0.007% a year and only replace 0.004% a year. This year 189k people will die, 114k people will be born.

Your argument is extremely relevant to some of the current AI Hype:

https://www.forbes.com/sites/michaelashley/2025/02/17/the-fu...

> Population of Seoul metro is 26 million people. It's suppose to drop by 2/3rds by 2060 (or worse). That's 1/3 less taxes, a 1/3 less transportation riders, 1/3rd less customers, etc....

If there are only 2/3rds as many people, why would the same infrastructure be required?

There's an infrastructure inflection point. Note how cities have much better infrastructure than country towns.

The problem is if you have overbuilt infrastructure, it doesn't just magically go away. You either need to pay to get rid of it, pay to maintain it, or deal with the consequences of letting it decay. Further, with an aging population, the decrease in their ability to pay for this infrastructure doesn't neatly balance out with a declining need for infrastructure. The retiree in poor health is more reliant on public transit, more reliant on healthcare, etc, while they both have less money to directly pay for those services, and contribute less to the economy as a consumer of manufactured goods or as an investor.

There is nothing special about any population number, it's how quickly and in which direction your population is changing that matters.

Yeah, in the limit, this is obviously false.

My hypothesis: Prosperity induces the population decline. That means there will be some momentum behind prosperity in the initial stages of the population decline. The population decline eventually induces a prosperity decline.

I'm guessing you didn't click through to read the paper.

Their take is that immigration policies rather than an aging population make the difference.

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