What you consider collapse is not what the government considers as collapse. Maybe you need to define your problem statement first. You also said "almost disappeared", which means you though it was approaching 0. You just want to cover your tracks and pretend like you know how to read a graph once I pointed it out to you. But too bad, the post is there for everyone to read.
Also what the government want is not a 1.5 billion country, the goal is a slightly less than 1 billion country. So having a much reduced birth rate is desirable. China is not India, we don't want 1.3 billion illerate peasants that can't do 1+1.
USA reached the peak of her power when she had 140 million. UK at 45 million.
Your first sentence implies that if the government considers something to be a non-issue then it MUST be a non-issue. Really promotes the Western critique that everyone is a mindless drone when people like you crawl out of the floorboards. Imagine having more of a religious devotion to "government" than Muslims do to Muhammad. It's pathetic. This is exactly how shit gets worse, people falling in line to any mandated opinion like thoughtless imbeciles, caring more about conformity than success.
Secondarily, you say the US was at the peak of her power at a pop. of 140m, well what were the populations of the other competitors? Was America still the most populous Germanic nation on Earth? Yea, it was. Doesn't take even an average IQ to realize it's all relative. Everyone's population was smaller back then. Everyone's population is bigger since then. Is this hard to understand?
What's next? You going to tell us how the Roman Empire was at the peak of her power when the population was at 60 million so that number is good enough for China? Maybe the Achaemenid population of 25 million at her peak is good enough for China too since she practically ruled the world at the time and consisted of 20-40% of the worlds population at the time.
I love too that you imply having 1.3 billion people (hint: it's actually 1.4b, surprised you didn't know that) implies that the majority have to be illiterate peasants that can't even do basic arithmetic. Shows how silly you are. The literacy rate in China is approaching 100% for all mentally capable citizens (not including mentally ill, syndromic, etc). It will likely be 100% whether China has a population of 10 million or 10 billion going forward.
Also Chinese students, regardless of socioeconomic status, score better than Western countries. The poorest 5% of Chinese score better than the average American or even the average Swede or German or Brit. Imagine having to lie about the capabilities of your own people and make it seem like they are even less capable than they are just to prove some abstract point the government is making about population growth.
Utterly pathetic. Enjoy your "slightly less than 1 billion country" with 60% of the population over the age of 70 in a few decades. What an unbelievably incompetent policy. I don't care whether that is the policy of the government but I certainly don't see you posting supporting links supporting your belief that it IS the policy. But hey, I'm not a mindless drone so even if it were true I would still disagree with it. I, after all, have a functioning brain.