In truth, overpopulation is a simple matter of biology. Different species consume different amounts of resources.
Humans, on average, consume huge amounts. The consumption is not at all equitable but, on average, that is what humans do - they divide into inequitable groups that consume very different amounts. This has been the case in every society in history.
Eight billion orangutans or dogs would cause considerable disruption in some areas, but eight billion H. sapiens is clearly to be unsustainable. If there were just one billion of us worldwide, most of our current problems would be gone. We would be sustainable, as long as we kept population in check. Then again, if there were just one billion of us, we would be less advanced than we are today. More numbers means more geniuses, which means more scientific breakthroughs.
More numbers then naturally results in more inequality as the best and brightest are paid well to help those at the top to entrench their power. If push comes to shove, any popular uprising today can be easily quelled with drones and automated weapons (invented by the best and brightest).
I see no use complaining about any of it, other than to vent. Yes, there's too many humans, who consume too much and are inequitable. When thiings go wrong, naive people will claim that [X people] are the cause of all problems, that everything would be alright if we just dealt with [X people].
The fact is that human animals behave - unsurprisingly - like human animals. That being the case, human populations are unsustainable.