Self-cherishing attitude is the cause of all our problems not just global collapse.
Industrial scale cattle farming is a must to support the current demand and it exists because we can't care enough to renounce the pleasure of eating meat. It is always me, me and me. And the problem is always because the other, the other and the other.
Of course we can sustain a lot of more of people, but not with our mindset.
There are already 8 billion humans, countries have destroyed 80-90% of their forests to put plantations to feed animals to feed ourselves and our children while we waste a big chunk of it. Not to talk about the tons of rubbish we create in the process and a pollution that may already doomed us.
And we want more and more. When will be enough? At 20 billion? Or do we make infinite children? Maybe actually stopping having children before it's too late is the essential for the survival of our species.
And for the continued functioned of society and the economy? Yeah you are right here. But again when will be enough? At 20 billion? Or do we make infinite children for infinite continuation of the economy? The economy is slowly collapsing already.
To be honest what you say is not my experience, what instances have you been browsing? There are a few tankie instances but nobody likes them, if you've been there I understand you.
I feel the users are very similar to Reddits, probably the 99% of users migrated from there for the reason that reddit sucks significantly much more than before and it is the same reason you are here too.
We are all defeated by the current events and nobody who isn't braindead wants WW3. Give it time, more users will migrate and with it more diversity. The community is growing so be the change you want to see.
But how do we reduce consumption? I believe that for whatever mess we are in we have to start by blaming ourselves, not just our personal problems. Blaming the other won't change anything. I blamed myself of all the world problems and I reduced my consumption to aprox a 90%, I started to use my car only when really needed, started to buy locally, cancelled all my shit and even went vegan, and I feel that I still could do better, sorry for the "holier than thou", I'm trying to give an example.
I don't really know how you got that my conclusion was to make someone stop existing. For a start you can't make stop existing something it doesn't exist yet. I also don't believe we should literally stop having children, but be more mindful of what we do, and that our mindset is the problem. The "I want this, I want that". But my other point was, do we really need more population when we do not have our shit together? We don't even understand what the problem is. We will consume to our extinction while blaming the other.