And in reality it was nothing but propaganda.

Which would be easier to sell: We are going to take over the world, make everyone speak German and move the Olympics to Berlin forever.

Or: We are building the third great empire. You know how well the other two worked out. Lasted a long time, right? So get on the winning side! Or, as Mel Brooks wrote, "Don't be stupid; be a smartie! Come and join the Nazi Party!"