The argument that "there are too many people and we need to reduce the population" has been for decades a thinly veiled excuse to justify eugenics. Which ethnicity's population are we going to reduce? How will the social mechanisms work to reduce population? Who will hold that authority to dictate things and how will it be enforced? Historically, very violently and strictly enforced against marginalized communities. That's how.
I literally said the problem is how we use them.
The issue is solely in our societal structures and our distribution of those resources
So the answer is we need to work towards societal change and structure ourselves to incentivize sustainability, not overly simplistic and unethical arguments such as "reduce the population" so we can maintain our shitty practices and kick the can down the road.
It also isn't "top 2-3 billion", it's more like "top 2-3 thousand".