prophecy and prediction are similar in the sense they both foretell the results of certain events yet to take place.
However the difference is the source. Prophecies come from spiritual gods or religion beings, belief system.e.g bibical prophecies, visions or dreams.
Predictions are made based off of scientific data, statistical data or trends of past events. e.g weather predictions, sports match predictions, election results predictions.
In this question prophecy is the best answer because the source of the outcome stems from negative thoughts of the pessimists which not based on any factual data but as a result of their own belief system and thoughts.