> I really don’t know where we went wrong, and I’m not sure it’s purely financial either (tho it is for many), at least from my anecdotal experience.

The problem is welly explained in the video: the society in East Asia (South Korea, Japan, China, Taiwan, etc.) is too toxic for the youth and it is too hard for them to live a decent life.

Young people there are constantly competing with others of their generation. Households are unaffordable for the majority of the population, and for the lucky ones, it takes approximately 30 to 50 years to buy one. Traditional culture encourages people to work extremely hard, to the extent that they don't even have time for social activities or to form relationships. Meanwhile, promotion is often difficult because management-level positions are occupied by older individuals.

People are stopping having children not only because they cannot afford it, both financially and in terms of time, but also because they do not want their children to suffer. It is expected that the situation will persist for generations to come.