This is pretty bad faith. It is very unlikely that you're responding to Hitler, of course no one is suggesting we murder 90% of the world's population, that is unspeakably evil.

But, with magic, imagine we had every technology we have now but with only 10% of the world's population. It _would_ be incredible, you could fly all over the world to your heart's content, your neighbor could buy a big diesel truck, and your friend could all the sushi they could ever want, and the world wouldn't notice. There would be immense open spaces, untouched, able to be enjoyed and the permanent residents, the plants and animals, wouldn't be perturbed.

That sounds pretty appealing to me, maybe it doesn't to you, but that is what someone is talking about, they aren't gleefully suggesting genocide. Now, how would we get there without magic? If I were king the first thing on my list would be educating children, specifically educated girls have many fewer and later children. Other things that drive birth rates down? Increasing quality of life, access to healthcare, and a strong social safety net, none of those things smells like bad things. I hope the next time someone suggests that you assume they mean doing those things over murder.

>Increasing quality of life, access to healthcare, and a strong social safety net...

I would wager that would increase the amount of people having children.

It actually trends down, likely because children have historically been used as a retirement plan of sorts, and of course you'd never be sure how many of your ten made it to adulthood.

Financially comfortable and well educated families tend to have less children, this is a pattern that has been repeated many times across country and cultural borders.