History has plenty of examples of nations and economies completely ending. In fact it's so consistent that it's basically a guarantee that the current economy you're living in will be "done" eventually. Therefore it's not a laughable conclusion but a valid possibility. We've seen two major economies descend into this "done" zone with no hope for recovery: Russia and Japan.

Additionally no one is saying to "not to do anything". Try all you want he is simply predicting the outcome of trying.