infinite growth is not possible in a finite system

That's one of the real problems. Economists and the people in charge have no idea what a successful zero-growth economy might look like. To me it seems pretty obvious. The economy may not grow in GDP or anything, but automation and tech advances mean that people spend less and less time actively working.

Let's say food production. In the past running a farm required dozens of farm workers. These days with automation one person might be able to do it all by themselves. If current farms produce all the food a country requires, you don't need more farms, and you don't need more farmers. No growth is just fine.

If cars are being made more and more safe, and more and more durable, people can go longer between buying cars. That means fewer cars being made, which means "the economy is slowing down"... but that's a good thing. Unnecessary production is reduced.

Part of the problem is that economies have traditionally been based on borrowing assuming more growth in the future, and having the kids pay for the retirement of the olds. Both those things need to stop. Some borrowing based on things improving in the future is probably smart. Things will probably be more efficient in the future, so there will be more surpluses to pay off debts. But, we shouldn't be borrowing assuming that the economy is going to keep growing at X% per year. As for retirees, have them pay for themselves. That doesn't mean you're assigned a 401(k) at birth and that's all you get when you retire. But, it does mean that a generation pays into a pension system during their lives, then is paid out of that pension system when they retire. It's ridiculous to assume that there's always going to be a pyramid shape to the economy and the big base of the pyramid will support the peak.

A shrinking population wouldn't be a good thing for humanity if it continued until humanity disappeared. But, it's unlikely that will happen. What's probably going to happen is that when the world is less crowded the population will stabilize. The optimum population of the planet might be significantly less than a billion, so it might be that the population growth will go negative for a while.