Or we would be just as stupid as we are now, just with an ability to travel in time instead of places, don't you think so? The greedy and egoistic thoughts, which destroy generations would not go anywhere IMO.
I mean, when I tried to tell Napoleon not to go to Russia, he didn't listen... oh wait, I was not supposed to tell this. Anyway, you should check people like Vanga or Messing, who kind of traveled to future (or at least saw the future (or at least they say so)). Nobody, including Hitler and Stalin, listened to them. The upshot? They all failed (thankfully).