He did not start WW2 alone - there had been many more people involved. The demonification of Hitler is one of the worst things historicist ever did. Instead of really looking for the mechanics behind it, they just created a monster to blame. If you look really at the facts about Hitler, all that is left is a guy who was good at talking, an elite of power-hungry cultists, which hid behind him, and a whole mass of industrials, nobles and scientists, who pushed this group into power for their own motives - from fighting the communist fever at that time in favor of unleashed capitalism to plain restoration of monarchy and feudalism.