My objection to runaway population growth, indeed from this point on any population growth, is not Malthusian, I believe technology will keep us fed, but one of concern for constitutional liberty and quality of life.
You can no longer build on property if the feds spot the wrong kind of varmints or if they espy a puddle. Your liberty of dominion over your property has been severely diminished. If it were not so, your property would become uninhabitable from the actions of your near neighbors. Your water and air would be polluted, you would not be able to sleep from the noise, they would vote you out of your property anyway. The next time you have to wait to go through Yellowstone Park ask yourself whether you want 400, 500 million people competing.
You have some points...but the bottom line remains - those with the population WILL get their way in the future world. Yellowstone will not be much fun to visit if the US is reduced to Third World status simply because we don’t have enough people to defend our interests overseas.