So in the whole anti-natalism/pro-natalism conversation (which I'm mostly agnostic/undecided on, currently), my friend who is a pro-natalist, argued that the success/stability of our world economy is dependent on procreating more children each year than the previous year, so that we not only replace the numbers of the people who existed from the previous generation (and some, to account for the statistical likelihood that many won't have children or will be sterile or die young etc), but also ensure that the population keeps growing in order to produce more and more human labor to "pay back the debts" of previous generations, because all money is borrowed from somewhere else... this is all very murky to me and I wish someone could explain it better.
She is also of the view that this will inevitably lead to population collapse/societal/civilisation collapse because we live on a finite Earth with finite resources that can't keep sustaining more humans & human consumption (and are nearing critical environmental crises), but that there isn't any other option than to keep producing more children because a declining population wouldn't be able to support itself economically either. Basically the idea seems to be that economically & societally we're on a collision course for self-destruction but the only thing we can do is keep going and making increasingly more of ourselves to keep it running (however that as individuals, we should be plant-based & minimalist to reduce our impact to the environment, non-human animals and humans for as long as possible). And she is worried about the fact that fertility rates are falling & slated to reach a population peak followed by a decline in the relatively near future.
As I said I'm not sure how I feel about this view but at first glance I think that the effect of having fewer children in providing relief upon the environment and helping safeguard our future is more important than preserving the economy because destroying the actual planet and life itself seems worse than economic downturns/collapses, but I really don't know enough about economics to say for certain.
I've always wondered why the consensus seems to be that it's 100% necessary for an economy to continue growing for society to function, but maybe somebody smarter than me can explain it in terms I understand.
Because for real, if (IF) we could set things up so that everybody has access to food, pottable water, and shelter, then does it really matter if google took losses this quarter? Back when automation was still in its infancy, there was a hope that the human labor requirements would decrease without affecting survivability, so it's not like what I'm saying is anything new. IF we were able to sustainably grow enough food, sanitize enough water, and build enough houses for everybody, make enough (NON-MONOPOLIZED) medicine for everybody, and just made it available for cheaply or for free, then you've successfully decoupled the economy from human survival.
Of course, the question becomes who would do all this with no profit to be had, which I know is the real crux of the issue, and is realistically not going to happen easily. But, as an idealist view, imagine this: A number of physically strong men and women and a number of scientists, who already have their own needs guaranteed, volunteer their time and expertise to spread the access to food, water, shelter, and healthcare to people in need because they actually just enjoy doing physical labor/ innovating technologies that will help humanity and aren't just doing what a few suits who've never worked in that manner a day in their lives think is necessary to squeeze more money out of investors and poor people in exchange for a paycheck. After those needs are guaranteed, it should be possible to implement a form of capitalism for unnecessary expenditures without getting to the awful state we're currently in (optional).
So to answer your question, no, I personally don't think infinite growth is necessary perse, but our current setup does assume that it will somehow continue growing. As for the societal collapse issue, while our society is FAR larger and more interconnected than anything so far in history, it collapsing wouldn't be the end of humanity (though on that note I would 100% rather society collapse from lack of labor FAR before I'd want it to collapse because Earth has completely run out of resources, so I guess I'm against your friend in that regard). Sure, there would be massive chaos (especially in population centers), and a lot of people will absolutely suffer and die (seriously, want to make clear I'm not making light of a collapse) but ultimately it still holds that anyone who can maintain access to food, shelter, and potable water (barring any health issues) will survive and eventually create a new society. Hopefully one that isn't setup stupidly.
You start running into issues with the economy when people are incentivized to not participate in it. People hoard money instead of investing it, industries that rely on growth stop which increases unemployment, and the economy becomes inefficient in general over time.
People generally think that no growth means the economy stays as is, but it would be more akin to a depression that never ends.
This is going to barely scratch the surface but, historically when economies contract people die but the rich get richer.
When top-down agricultural economies contract (negative inflation) that means there is less food around this year than last year. If that happens enough times there's a famine, but it's not those rich in food stores that will suffer the most. It's those with the least food because they'll run out first.
When top-down capital economies contract (negative inflation) there is less capital around this year that last year. If that happens enough times there's a recession/depression, but it's not those rich in capital that will suffer the most. It's those with the least capital because they'll run out first.
In either case the problem in my opinion at least isn't that the economy contracts, but that those are the top don't share their wealth because those in the middle are so afraid to lose theirs they're not willing to take it from the rich. That's because the middle doesn't realize how far away the rich actually are from them and they're worried that if someone goes for the rich and powerful then someone will also come for the mediocre money too.