Port Arthur Dot Animation

It's like the Columbine version.

I know little about guns,but based on this animation it seems to me that it was "easy"(no disrespect towards the victims) for Bryant to did what he did at the Cafe. His Victims where cornered and couldnt react to the threat. Thats why i dont understand the conspiracy-theorys, claiming Bryant was too dumb to carry out something like this.Shooting defenseless people in a close and crowded area requires not much intelligence, and obviously he knew how to maintain his Rifle (reloading,firing etc.) Is there any other Motive besides getting famous?(as far as i know he was influenced by the Dunblane-Shooting)