Governments have CAUSED the so-called population problem. Their pandering to bankers through deficit financing and bailouts, allowing them to steal nearly all of the public's productivity gains have left people with a situation where it is very expensive to raise kids if you're not on welfare. As a result, you're seeing people not having kids until their 30's now, and having *maybe* 2 of them.
Add to this the completely biased court system in western countries that make it absolutely profitable for a woman to get a divorce, leaving the guy eating dog food and living in a dank, rented basement while he pays for her and the kids every needs, while being lucky to get weekend visits with his kids that aren't supervised, is it any wonder that guys have little desire to have kids?
Oh, but now that the baby boomer generation is dying off, and we're normalizing the population trend again, it's this huge fucking problem because of the broken system our corrupt politicians set up that demands infinite growth in a finite world or their fiat system crashes. So let's haul in millions of immigrants as fast as we can to patch up this problem, and in typical government fashion, create a new problem on top of it. Let's not even think about what happens when a critical mass of them stay on welfare and don't contribute to the system, resulting in net-loss to the whole fiasco, making things even worse.
The resulting implosion will be spectacular, to say the least. I'd rather not be around to see it though.