Modern life, particularly social media exacerbates brain rot. It sells fantasies to people which creates unrealistic expectations of reality for sex and relationships. Men expect women to look like influencer models and they refuse to date normal women while women only want men who are rich and successful like they see on social media or don't act like the love interests in romantic fiction. It encourages people to cloister themselves in individual bubbles chasing frivolities instead of interacting with each other as a holistic community and it is only made worse by the high expectations for education and work performance.
Unfortunately, the very things that make Asian culture very successful are also their undoing as having a very strict and competitive society makes it hard for people to have kids and flourish. Add to the fact that Asian cities are densely populated and highly developed which are statistically the worst places for fertility and you have the makings of an ever-escalating crisis. When it comes to high fertility, what you want is to have a lot of stupid, poor people with lots of risks and danger (to create sexual tension and motivate coupling) which is precisely the opposite of what a successful society is. It's almost as if civilization itself is a natural bottleneck to population growth and advancement; kind of like how having a rat utopia created a behavioral sink in the population.
Ironically, Indians might end up having the last laugh. Not because their country is successful but because they're so backward and poorly managed. Timing is key, so while they might miss the globalization trend for manufacturing, they have huge opportunities in the service market as caretakers, convenience store employees, day laborers, and other low-level jobs in the US, Middle East, and Europe. While the rest of the world struggles with demographic declines and needs cheap labor, they will have a large young population with a replaceable fertility rate to export all around the world. This allows them to spread their genetic seed, cultural traditions, and social beliefs globally far better than China in 50 to 100 years.