The fantasy is that an economic system predicated on infinite growth can be made compatible with finite resources. Take, for example, the fact that renewable energy keeps growing as a percentage of total energy generation, yet total GHG emissions keep rising. That's a result of the system of incentives set up by capital. Yes, the economy can become less coupled to resources (as it has), but there is a limit, unless you seriously want to argue that iron (for example) can be an arbitrarily small portion of the economy.
An economy is a method of allocating resources. This economic system is extremely terrible at meeting base human needs (consider that we produce many times the amount of food that's needed to feed everyone's needs, but massive amounts of it used for industrial meat production and biofuels).
> we are never returning to pre industrial times
This is an absurd strawman.
> everyone needs to become poorer
This is, in fact, the industry propaganda. What degrowth advocates for is taking as our first priority meeting human needs and living sustainably (which can be made compatible with most of the technology we have today in some form), rather than the ideology of growth for growth's sake, which mainly results in massive amounts of wasted resources and funnelling wealth into the hands of a few.
> “Hey Africa, we know we colonized you and all but can you do us a favor and stay poor to help fix the problem we mostly caused?” There is not enough “fuck you” in the universe for that one.
This is misdirection. Getting water, food, shelter, and medicine for everyone on the planet is well within our means as a species. It is the ideology of free movement for goods but not people and infinite growth that makes it impossible to meet those needs, because it requires and underclass who can be used for cheap labour and contained in states built for that purpose.
It's not poor people who stand to lose from degrowth, it's the ultra rich.