Hitler was actually helped as much by his lack of charisma as by his charisma. To sophisticated thinkers he appered to be an ignorant blowhard with no imagination. As a result he was not taken seriously by his enemies until too late.
Most history programmes show Hitler in full rant in front of a crowd and here he seems charismatic provided no subtitles are provided. When English subtitles are added in (as this programme did) Hiltler suddenly appears to be an empty shell of a man who says almost nothing at great length and volume.
Hitler always believed that great men could mould a nation in their own image and he seemed to prove this in his own career. In fact leaders are less powerful than the Hitlers of the world believe. They may release forces that already exist but cannot create them. This is good news.