To answer the original question... you can't destroy the economy, so I'm not worried. You can destroy the financial system, but not the economy. So long as some people want things that other people have, and are willing to pay for them, there will be an economy.

As for people being put out of work by machines.... this is already happening and has been a continual trend. There won't be any one moment when suddenly machines replace everyone, but just the slow gradual automation of various tasks that we have been living with for decades now.