So, no, placing a knife in your teeth and hurling yourself through time to kill Hitler isn't quite the no-brainer you think it is. Also! What if you went back in time to kill Hitler and then fucked it up? What if you didn't kill Hitler, and he stole your time machine, you colossal dicksore? Hitler now has a time machine! How fucked would we be then?
To find out, I programmed my computer to simulate every event in the world over for the past 70 years, assuming Hitler had a time machine, and then let it run over the weekend. Here's what it told me: