You're using an index graph which isn't relevant.
Yes, I know back in the 1980s, the US had a population which was approximately 2x larger.
The argument still stands.
What were the chances of the average Japan person being 2x richer than the average American?
And then the Japanese economy would only be equal to the USA.
For Japan to overtake the USA as a superpower, would have required the average Japanese person to be at least 3x richer than the average American.
Once a country catches up, it is difficult to grow fast because you are at the technological frontier.
Plus it's straightforward for other developed countries to copy whatever you do and to keep up.
Then I assume you agree to my previous post about the theory of 2 axis of growth
Given that Japan is going for 1 axis of growth vertically which is increasing people's income then it will (and has already) hit a 'soft' ceiling where it becomes increasingly difficult to increase the income
However China due to having 2 axis of growth:
1st Horizontally having many people
2nd Vertically increasing people's income
So by having a basic gdp calculation of:
People * People's Income = GDP (potential)
Then you see that China has gotten a tremendous opportunity for "easy" growth. So why should China deliberately limit its 1st axis of growth which is the population?
Also lets keep in mind that very soon that 1 axis of horizontal growth will become 1 axis of horizontal DECLINE due to the population aging and shrinking workforce
Now China has transitioned from:
People(Growth) * People's Income(Growth)
To:
People
(Decline) * People's Income (Growth)
So China has a structural declining GDP factor to constantly counteract, cancel out and outgrow. This is all bad news
Ofc I am just talking about the most basic drivers of GDP growth and I am neglecting other factors. See India for example...