From Jared Diamond’s Collapse: How Societies Choose to Fail or Succeed:

Today the world no longer faces just the circumscribed risk of an Easter Island society or Maya homeland collapsing in isolation, without affecting the rest of the world.  Instead, societies today are so interconnected that the risk we face is of a worldwide decline.  That conclusion is familiar to any investor in stock markets: instability of the U.S. stock market … affects overseas stock markets and economies as well, and vice versa.  We in the U.S. (or else just affluent people in the U.S.) can no longer get away with advancing our own self-interests, at the expense of the interests of others.