Frankly, I am flabbergasted that there are even people saying with a straight face that there might be no problem.
It is so darned obvious that there is.
Edited to add: since there is apparently a need to spell it out, here are some reasons why we must indeed attempt to reverse the current trends.
1. Human demographic problems are, by their very nature, politically difficult to handle and take literal generations to even attempt to address.
2. Human multiplication is, and has always been, geometric. Our ability to handle the resulting challenges most definitely does not grow geometrically, and even if it did, that would hardly be a free pass for neglecting those challenges.
3. Humans have been rather demanding of each other and of the environment, in several different ways - politically, economically, socially, and even by a purely cultural perspective. We have actually reached the time in history where there is actual hatred between competing narratives, and a stream of hope for destructive confrontation to "solve" those tensions feeding that hatred. Those are formidable, very tiring, very wasteful and demoralizing challenges that will not go away any time soon, and only become more difficult to address as population numbers rise.
4. The planet itself is very much a finite resource, and talk about going to other planets is ultimately a pipe dream. It is not like the resources for significant migration are even conceivable, nor would that be an actual solution for the demographic pressures in any case.
5. As significant numbers of various overlooked minorities grow, it becomes that much harder to even understand the actual challenges ahead of us, let alone solve them. And the actual measures used become that much more gross and destructive even when correctly chosen and implemented, as well.
6. One of the most dire aspects of the current trends is massive cultural and economic estrangement. Wealth distribution has become so loopsided that there is actual willingness to doubt the very existence of the empoverished masses. That is a very dangerous, very unstable situation.
7. While our cultures have become more ambitious and more specialized, there is always the need to sustain the weight of that ambition, both economically, socially and in the educational aspect. Every achievement needs a multitude of effort to support it. As populations grown without properly addressing the flaws and injustices in those support structures, those flaws become grimmer and more destructive.
8. In order to cope with the various forms of loss of quality of life, we have been increasingly more accepting of chemical dependence and other forms of alienation. That amounts to effectively giving up our own ability to accept reality and deal with each other. Both a result and an aggravator of the other problems caused by overpopulation.
