It is interesting, is it not, that Germany had a low birth rate and open sits doors to thousands of immigrants while Britain feels overcrowded and devolves into a deep set racism, and China faces a crisis of a falling population.
Why is this a crisis? We can easily see too many people in one place leads to enmity but the numbers of people in a country is directly related to how militarily capable and economically viable that country is. The idea that more people means more knowledge is secondary. Falling birth rates always mean more educated women, and that is never a bad thing on any measure.