As anyone who knows me can attest, I'm a stong believer in the idea that all government money and private charitable contributions should be diverted towards the discovery of time travel. I mean, provided time machines are in the hands of good guys and not evil robots or Biff from Back to the Future (and its sequels), every awful thing about the present can be prevented. (That is, if you believe in the Terminator/Back to the Future theory on time travel, that you can change the past, and not the 12 Monkeys theory, which says "what's done is done"). We could go back and tell Henry Ford not to name his son Edsel, we can go back and tell Elvis to lay off the snack foods, and we can go back and tell the guy who got AIDS from a monkey to not have sex with humans (once you go ape, you never . . . have sex with people again. Ever.). But most importantly and obviously is the Hitler thing.
Imagine going back in time to Vienna where a teenage Hitler, who was basically the first Emo Hipster artist douchebag, was trying to get his art sold and make it into art school. Imagine saying to the young whiner, "hey dude, your art is really neat and I bet no one understands you, correct? Have you considered going into the film business? You don't even need talent to get into the movies!"
Then of course young Emo Hitler might point out that Hollywood is full of Jews, at which point we'd say baloney, Jews were never really good at show business, they're too busy being football stars and dancers, now come on you angst-ridden teen, let's introduce you to Louis Mayer and the Warner Brothers, none of which changed their names from something far more Jewish. Then Hitler spends the next few decades making weird arthouse films that only beatniks will watch, probably be one of the guys who married Marilyn Monroe (she'd famously say later that Hitler was slightly less brooding than Joe DiMaggio) and maybe end up on a Hollywood blacklist in the 1950s (I could easily see Emo Hitler going communist).
Of course, as is always pointed out in time travel movies, changing the past can have unforseen and not always terrific consequences--maybe with Hitler out of the way the Nazis would have an equally evil but more competent leader, maybe the Soviets would loom as a greater threat, who knows. But the beauty of the time machine is if what you change doesn't work out, you can always go back and fix it again. What could possibly go wrong?