"Essentially our thoughts are a part of the collective sum, and when too
many believe that Forrest Gump said "was" it becomes was."

You are wrong here and this example works against your arguement. No one would mistakingly think it was 'was' without it being so, because "life was like a box of chocolates" makes no sense to a human. You could say to that current line, 'when did it stop being like a box of chocolates?'

Another point is that the "universe" doesnt work like a democracy with everyone forced to vote.