imagine you do that, and the guy still does ww2, and that was your only chance.
Now imagine, you do that, and the guy is born much smarter, and he actually wins, and that was your only chance.
Ofc he still does the war, otherwise why would you go back in time to have sex with some Austrian chick?
(But WW2 was happening anyway, that's why we went back in time to kill that tourist in Serbia)