If even a giant organization like the government cannot prevent a crisis, then what are those economists? You need to remember one more thing, they are talented, they have great research works but that does not mean they know everything in this world and can solve all problems.

I am sure that even when you are having difficulties in life and you go to financial advisors. They can't even guarantee that they'll get you out of trouble, let alone a country's economy. What they can only give you are the ideas they learned from books and whether it will help you succeed or not, they themselves don't know anything.