Once you predict this, you can never take it back. Mercado Libre, Business Insider Economic forecasting is a difficult game — get it right, and you'll get not only plaudits, but potentially a lot of money too.

But get it wrong, and you'll never be able to take it back. Your predictions will live on, and potentially sound extremely funny one day.

The past half a century is riddled with grand projections about national economies and the way the world is going. Some have aged much worse than the others.

These are some of the very worst.