While a lopsided population pyramid does cause issues, it's not the end of the world for a lot of countries.
A lot of the population doomerism I'm noticing started off as a Zeihan or Perun trope that was repeated ad nauseum on certain subreddits and percolated into the HN world.
If you want to see a country that has been old before it truly became rich, just take a look at Thailand.
They are a large country with a very low TFR, a high median age, and a low median household income ($7k/yr) yet they have not collapsed.
Most of this is because of social welfare - most high revenue industries are very highly skilled and this require a small skilled or semi-skilled population.
Think industries like Automotive, Semiconductors, ONG Refining, Finance, etc - this is the Thai economy (tourism is actually a relatively small portion compared to those).
Deploying tax money generated from those industries into social welfare such as expanded healthcare, expanded social services, etc helps minimize a lot of the issues at hand.
Japan's population has also been shrinking, for decades now, and it's the same story, as has Italy's.
Countries like Japan, Italy, Korea, and Thailand do supplement their unskilled sector with migrant workers - they just don't get counted as immigrants (eg. Most "Work Trainees" and "Interns" in Japan and Korea are actually Indonesian and Vietnamese migrant workers who are doing low prestige jobs like gutting fish, working at a below minimum wage factory, cleaning toilets, working at nail salons, etc)
And workers will always chase a higher salary - the same Thai people who wouldn't clean toilets (and thus depend on Cambodians, Laotians, and Burmese to do it) would clean toilets in Korea, and then Koreans themselves try to emigrate abroad to the US or Canada because of better salaries and easier work culture, etc.
Realistically, Korea will leverage the Vietnamese population pipeline (it already has) and maybe NK down the line if relations start to warm up again.
> population doomerism to HN. Why do you think this is relevant
Because as we age society will 'somewhat' collapse. There will not be enough people to do the work. The idea young workers will be imported from other countries doesn't add up. Nursing homes are currently disgusting places and lacking skilled workers.
Nursing homes need to be 'disrupted' so they can handle the incoming load (and the current load) is one obvious reason it's relevant to HN.
> or that a trend dipping negative for a while will inevitably continue that way?
Of course it will. Unless you claim this is Covid deaths. South Koreas birth rate is .7 the lowest in the world, that is what one assumes is at play.
As far as the birth rate or population rising again it will take a significant technological event. AGI will do it for instance or longevity drugs. But there can be large pain points before we get there which is how the graph is heading.
Probably because it's presented as a problem to solve (we don't know how we're economically going to deal with it) and engineers love a challenge, even when they're not experts in the field. So same reason why urban planning issues, etc often show up.
In 1927 world population was 2 billion - now, less than a century later it is 8 billion. In the 1960s world population grew by 2.1%. For most of history until about 1700 or so that rate was about 0.04%.
The world population growth rate right now is much higher than it was in 1900 (and 1900 was higher than 1899, which was higher than 1898 etc.)
There's not really that much to population doomerism if you look at the historical trends. The only thing to it is that the growth rate in the 1960s was probably the highest in recorded history, and we are not still at that peak - but the world population is still growing faster than it has from 4000 BCE to 1940.
The other thing is it varies from place to place. Uganda's population is growing faster than the world rate, whereas Latvia's population is currently shrinking.
(Of course these things are all estimated, no one knows exactly when human population hits exactly 8 billion people etc.)
(meta-comment: someone keeps posting population doomerism to HN. Why do you think this is relevant, or that a trend dipping negative for a while will inevitably continue that way?)