It is possible for the two following statements to be simultaneously true:
* the ability of collaborating groups of humans to achieve/produce scales super-linearly with the number of humans[1]
* the growth of human population is causing problems, and is likely to cause more problems in the future
One reason is the scarcity of resources[2]; another is that "humanity" as a whole is not collaborating with all of itself.
[1] actually, I don't even think this is true, beyond some limit - but it's true for small groups
[2] which could be mitigated somewhat by fairer allocation of resources, or by process changes to focus more on fundamental needs; but, still the fact remains that the resources that we have access to on Planet Earth are limited, and access to extraterrestrial resources are extremely expensive
What is a fairer way to allocate resources than you produce for me and I produce for you?
Seems to me any other system is open to being gamed. Sure there are people born into generational wealth. But those are like one in a million and generational wealth doesn't typically last more than a handful of generations as the number of descendants grows exponentially.
This is why I don't trust anybody who tries to tell me that human population growth is an actual problem and not just our rulers' fear of irrelevance.