> What millinials and zoomers are really struggling with is the hallowing out of the social and economic institutions that supported our collective wealth and well-being.
It's multi-dimensional, not even limited to just that. We are living in a world of increased scarcity. The deleterious effects of an increasing population are very real. From a labor point of view, it's not just increased labor supply resulting in devaluation of said labor. There are tighter margins in the managerial and corporate level of things as well. Modern societies are complex things that attempt to cover all of their bases by inventing whole portions of economy through structured, financial support from the top down. This means that on a fundamental level, additional capital must be appropriated by the organizational arms of society, including the cost of labor to organize and implement such a thing to begin with, which further reduces margins for the managerial class and for the labor class. On top of that, these can be counted on to compound the effects of increased competition at all levels in the relevant industry through artificial flow of capital sustaining said competition that otherwise wouldn't exist. The idea is that more people, more labor, more value, win/win/win. But in practice, we're already burning a mind-boggling amount of entropy attempting to establish some sensible bare-minimum degree of equity. More labor just means a greater degree of a fake and "manually" structured economy to stop whole swaths of society from collapsing in on itself. It's not to say these systems of equity are bad, but they prop up an inflated population number and THAT reduces the relative importance (and thus power) of everyone as a result.
We also have to account for changing climates. Celestial systems aren't static in the slightest, and the status quo changes quite radically and quite frequently. We're currently living in an ice age. During a hot house period, the overwhelming majority of earth's surface ends up being about as habitable as mercury. Even without anthropogenic climate change (which probably just tipped the scales), the fact of the matter is that the climate changes by itself too. It wasn't that long ago that MENA was a lush, green paradise. Only 8000 years or so which is an infinitesimal drop in the bucket. At some point, we were going to enter another hot house period where only a couple coasts are habitable. Wanna guess what that's going to do to scarcity?
Of course, to whatever degree these things exist have no linear, predictable relationship with some single-value macro (or even micro) economic KPI. The highly chaotic system of society is full of nth degree causal feedback loops which are completely beyond prediction. There are nigh infinite more problematic effects of growing populations as a result, I can't hope to be exhaustive about it, or asterisk every permutation of these abstract causes and effects.
There's a lot of rhetoric to be found which assures and assuages that thermodynamics isn't real. There is no relationship between population and scarcity, or if it does exist, it's very minimal. We're not operating efficiently, and we need to do that before we start to examine the relationship between population numbers and quality of life. The convenient part that they leave out is what a society built around "efficiency" (in the sense that they mean) actually looks like. We already have places where humans live according to extreme principles of efficiency: Submarines. It really is efficient to live in bunk beds and eat in cafeterias. Not sure many people want to live like that though, so why the fuck are we trying to build such a world?