My theory is that we cannot because we don't share and prosper together. We have "trickle down" economics, which IMO means current economic incentives are pyramid shaped.
In order for the pyramid to grow in size, the people at the top consonantly need more people at the bottom, consuming, to keep it growing.
If the economy was "rounder" and more directly beneficial to everyone, it would be less necessary to have more consumers / population growth.
Population growth expands general demand and markets, and really sustains some industries (construction, for instance), but is not sustainable, indeed.
If population growth stalls or even if population shrinks then the overall economic output will do the same. But IMHO that is not important, what is important for people is the economic output per capita and as such I think it's possible for people's lives to continue to improve.
Most first world countries have an infatuation with construction and property that seems unsustainable, especially as property prices rise and land ownership continues consolidating up the economic ladder.
A few countries have caught themselves in a bubble, and my country in particular (Australia) does everything it can to make sure it doesn't pop. There are numerous government grants for home-buyers, every time we have a financial crisis it's the construction and banking industries that get all the grants and bailouts, and even during the various COVID lockdowns there have been schemes to prop up construction. Government and council platforms are almost always based around construction projects, rarely reform or social programs.
I get why, without these schemes, the house of cards would come falling down. But at some point endless construction will have to slow down, and we'll need to make a more sustainable relationship with construction and property.
In principle, but if economic growth is still physically possible then anyone trying to stall it within their zone of political influence just gives relative power to those who don’t.
> Can we achieve prosperity without economic growth?
It's extremely difficult. Progress is almost always related to new products and services. Imagine developing those under the constraint of no economic growth. "We can't grow economically, so we can't develop this new vaccine unless we close all the coffee shops in town."
> Because at a point, we sure can't have prosperity with continuous population growth.
That's a different thing. In theory, one can have economic growth without population growth, at least for a time and in certain range. The economists call it "productivity"[1]; it measures how big is the lever that each worker uses to produce. I guess that we could, with the current population of Earth, have sustained economic growth without population growth for centuries, just by equalizing-up productivity across all population sectors and countries.
With that said, even the current human population of Earth is quite a stress on the planet. In the best world, we would find more and better places to live, so that we can leave our planet be and have the freedom to have families as big or small as we like.
In order for the pyramid to grow in size, the people at the top consonantly need more people at the bottom, consuming, to keep it growing.
If the economy was "rounder" and more directly beneficial to everyone, it would be less necessary to have more consumers / population growth.