Why do you think that perfectly predicting the future is fatal?

Perfectly predicting the future causes one to become a prisoner, or a victim, or his or her own fate. By being able to see the future but being unable to alter or change it, one is reduced to merely becoming a passive observer of one's path rather than being the one to walk it. Additionally, attempting to alter the future winds the webs of time tighter and tighter around a person as he/she becomes trapped by his/her choices and the complexity of his/her future.