"We" can do whatever we want but if not "everyone" is doing it then the impact is fairly limited.
You would be better off having children and just consuming less than making a grave decision that impacts your whole family tree for the sake of a Humanity collective that likely will not be making the same "sacrifice".
Indeed, who is to say that the perpetuation of one’s family tree is at all desirable or necessary?
Maybe the best outcome is not to play the game at all.
How many families are large because the person who had to be pregnant had no real say in the matter?
Edit: Not only are there natural corrections that occur, there is also a lot of room for human-made "corrections". Is it ugly? Yes. Is it unfair? Yes. Will it ensure that the local economy continues to function? Yes. The vast majority of us in such a scenario would live in poverty.
(This is where I go off the deep end) Imo, the proliferation of LLM's will truly lead to massive amounts of people being displaced from meaningful work. I foresee that in the not-so-distant future "normal people" who didn't attend elite institutions (or who are otherwise not extraordinary in some sense) will only find "flesh work" available to them - i.e. prostitutes. As long as human flesh exists there will always be work for humans. It's dark, I know, but ask yourself if it's true.
Disclaimer: I find prostitution appalling and sad, but it's existence is no secret.
Like working into your 70s
For instance, when we're told we need to eat less meat, we'll it's not so much that meat production is a problem, it's that meat production for billions of people is a problem.
So all the constraining measures we're seeing either being suggested or enforced "for the environment/climate" are constraints to fit so many people on the planet.
Would 15 billion people be too many? 20 billion? Are we to imagine that Earth could support an infinite number of people? Because that seems like magical thinking to me. Though a different lifestyle (vegan, low energy consumption, etc.) would probably allow the current number to get by fine.
Talking about how many people can be sustained by earth is talking about the wrong thing. It only leads and HAS only lead to the eugenetics part. Because it's always poor people in different countries who gets sterilised.
The real topic is that capitalism and consumerism is 100% unsustainable, right from the start. That is the real debate to be had. That this world is not about human well-being and happyness, but about GDP and growth, making a tiny number of people wealthy at the expense and misery of the majority.
Unfortunately this site - Hacker News - and everything related to it, Ycombinator, Paul Graham, is only fueling the capitalist game.
You talk about "sustainable population", there's nothing not to understand about this. Sustainable implies it's now unsustainable, but that notion isn't true.
Why do people insist on making this an eugenics talking point?
The number of people is not the problem.
For what it's worth, I would be delighted to live on a planet of 10 billion people who have found a way to live in a way that can persist for millenia, but we don't seem to have done so. Although, living in a well-insulated flat made with renewably-grown timber (a great carbon sink!) walking and biking distance from all of my daily needs where my meagre energy needs are met with 100% renewable energy (when I lived in San Diego I worked from home and our apartment's average load was 100 Watts so this can be done!) on a mostly-vegan diet and working 20 hours per week or less sounds pretty nice to me.