The problem with Malthusians is that they see people just as stomachs which need to be fed.
People are indeed born with stomachs, but also with hands and brains to provide for themselves.
True, of course. That’s what enabled going from 1 billion to 8 billion in a short amount of time. But you need inputs — arable land, water, nutrients, ores, air, etc. Do you think these are infinite?
Can the globe support 25 billion souls? 50 billion? 100 billion?
No matter how clever you are, with no inputs you have no life. Maybe the ore inputs will come from asteroid mining. But water and air?
The issue is exponential unbounded growth vs the “logistic curve” which is asymptotic to some limit. It’s also whether, as you approach that limit, the systems will turn chaotic and possibly suffer some massive collapse.