I think all the very empirical, rational arguments you’ve gone through in this post probably don’t enter the heads of most people when they decide to have children. People have children because we’re hard-wired to want to have children. It doesn’t mean it’s not a bad idea in the wider context, but people don’t think about that.

So any move to discourage people from having kids is doomed. Think about everything you’re asking (not quite the right word, I know) people to give up throughout the whole course of their lives just to drop the population one miniscule notch on a graph…

The population will decline one day because something awful happens to make it decline. Some sort of human society may well emerge from the ashes in diminished numbers. Those people will probably be no more or less happy on average than anyone is now. It doesn’t, in the end, matter.

Plus longevity is a very significant contributor to the rising population as well, you can’t just look at birth rates. Thankfully the current government’s plans to comprehensively fuck up the NHS should go some way to addressing that.