There is a book written by Jared Diamond (the guy who won a Pulitzer Prize for “Guns, Germs, and Steel”) called “Collapse: How Civilizations Choose to Succeed or Fail”.
Germany and most of Western Europe has simply chosen to fail. I think Toynbee said that civilizations are not murdered but commit suicide.
I read that book years ago...pretty good book until I got to the end and of course.....wait for it.... global warming was the real reason civilizations will fail...