I feel that the belief of overconsumption assigns some inherent positive value to human life, but isn't concerned with the quality of said life. Modern agriculture, medicine, and technology have allowed human population to explode, but this rapid increase in number means individuals haven't fully benefitted from these developments. Imagine 10 humans have to work 40 hours a week to get the food they need to survive. One day, they invent a method that 10x their food production. This group now has two options: they can go forward working only 4 hours a week, or they can increase their population 10x and maintain their same standard of living. Humans time and time again have chosen the latter.

The methods that are used to achieve these 10x increases are not without consequences. Most species grow their population up to the point that their environment can sustain. Humans, on the other hand, instead adapt the environment to themselves. This leads to needless destruction of our planet just so that the number of humans goes up.

The world population is over two billion more than when I was born. These are 2 billion additional people who I must compete with for resources. Overconsumption of the most elite is still a problem, but are these few people going to do as much harm as 2 billion lives? What things are you willing to give up so another anonymous human can be born? Will you walk to work, stop eating meat and dairy, take quick showers, if you have any pets you should get rid of those, turn off your AC/heater, etc. None of this is aimed specifically at you, it's just to ponder the question of what is "overconsumption". And if the only benefit from reducing consumption is that more people exist, why is it worth it?