If you could see the future of humankind, would you?

My sister and I were having an argument today about this. She was saying that if she could, she would travel to the future to see the decisions that humankind has made. She would then use this and possibly try to save human kind. But I think she is wrong because in my opinion it would do more harm than good. If humankind has made wrong decision and you tried to fix it, you would ultimately be messing with too many fragile and important points of time. Things could spiral out of control. Morally, I don’t think that one person should have the right to choose the path for humankind. What is your opinion?