Jared Diamond's take on collapsing societies is widely praised and a lot has been written. I don't want to add to much to that, other than a few notes:

• One important message is that societies are actually fragile and often collapse. Many seem to neglect that. Civilisation is not a one-way street uphill.
• It is actually filled with interesting facts about collapsing (Easter Island, Mayas, Greenland Norse, Rwanda, etc.) and successful (e.g. Japan) societies, as well as currently endangered (e.g Australia)
• Diamond has a 5-point framework to address the problems of societies, but here is an even shorter take-home message: Two types of choices have been crucial [for societies]: Whether they employed long-term planning and if they had the willingness to reconsider their core values.
• This book spent some time on the shelf because I found the introduction about Montana to fact-filled. If you read this, skip what you find boring. That's ok.
• Diamond gave a 16-minute TED-talk on this. Disregard the combover and that he didn't bring slides, he is a 70-year old-school professor :)