Humanity is going to always consume more than it creates. I'm not being misanthropic, I'm just being understanding of the majority. Certain people are NEVER going to be convinced that having more children than they can support, raise, nuture, teach, etc is bad for them. And how exactly are you going to teach them? If you put a child limit then they'll just rationalize their actions against a "us vs oppressive government" scenario where you're the bad guy trying to destroy families.