One of my friends would erase three generations of his own family by going back in time to kill Hitler. His entire existence depended on his grandad coming back from the war and finding his family had been killed in the blitz, leading him to start a new life which resulted in the current line.

I imagine a lot of people would be similarly affected by going back to assassinate Adolf. Similarly, I could remove four generations of my own family by preventing WWI from happening.

Of course, a lot of people might look at this altruistically and conclude, "A lot more people died because of Hitler, and in much worse ways, than the number of people who would be lost (presumably instantaneously, painlessly and without record) because of his death" and then go back in time and do it anyway.

But it's never as simple (one would presume, depending on how timelines work as you pointed out) as "go back in time, kill Hitler, everything else continues as normal." There's a very high chance (especially if you live in Europe or one of the other main theatres of war) that beyond the obvious side-effects of the last 70+ years of history being radically different, you would completely erase yourself - and/or many of the people that you personally know and love.