First off, I'm not saying that kids are bad or that White people becoming minorities in their own counties is good.
I'm saying that if you have 100% ethnic purity in your nation, then having your population always grow isn't a good thing.
Do we want everyone living in 300sqft boxes? Do we want 30m super cities made of worthless materials sprawling our land?
For example, people are freaking out that Japan's birth rates are the lowest ever in the 20th and 21st century. If you do the math, that merely means that Japan's population if these birth rates continue will stabilize at roughly the same population Japan was at I'm 1900 of 45m people. That's fine. Japan doesn't need 120m people not does it need 200m or 300m.
We could all use with lower population. Of course, I want that lower population to include the lesser races and I don't want White people replaced by immigration. Those are separate issues. If we have the power to increase birth rates collectively as a society, then we have the power to deport all non-Whites and stop giving free gibs to non-Whites.
Why can't we afford to care about deporting all non-Whites instead of just having more children? Have more children if you want and by all means, that's fine but the focus should be on deporting all non-Whites.
If we had zero non-Whites, I would still encourage people to have kids.