In the sideways world, Ben went to an island with his father who took a job with Dharma. However, in the sideways story arc, they left the island for an unknown reason. Ben finished his education. He received a doctorate in modern European history and came to be a high school European history teacher.
We can assume in the sideways story arc, everyone is dead because that was what we were told by Christian. The question remains what about the overlap elements and events. Which came first, the chicken or the egg; the island or the sideways realm?
For this discussion, we assume that the sideways world is the true barometer of the series "reality." In this situation, we have Ben actually having a normal single parent childhood (abet with a short detour to the island run by a cult leader), but he is well grounded in a responsible position as a teacher. He lives with his father which means that they got along. However, for whatever reason, sideways Ben may have resented his fate in life; he did not have power or influence nor the character to change his lot in life.
He is a single man who has devoted his life to learning about history. History is repeat with stories, chilling characters, epic battles and dangerous amorous plots to overthrow powerful rulers. He would have known about all the trials, tribulations, contests, and personalities of historical figures of Europe and the lands of conquest. That information would have been fertile ground for Ben to imagine himself transposed amongst the greats in history . . . to create his own personal fantasy history.
The island also contained the classic elements of history: rulers and followers, conflicts between bands of people; treaties, conflict, war and bloodshed; seizure of territory, to genocide. Ben transposed himself into the island just as a historian would imagine what those times were like in order to understand the motivations and mistakes.
Ben was an unhappy follower. He found an opportunity to join the enemy. In order to prove his worth, he engineered the Purge. He killed his own father, which in many ancient cultures was the means to confirm and inherit power of the tribe. He began to rule like a dictator. He used fear to balance the politics of his inner circle. As he amassed more and more power, his vision of himself became grander - - - Napoleon in some respects. Instead of conquering other lands, he decided to conquer people: capture them and make them respect him.
Ben dreamed of a world where he was the center of power; a pharoah like god among men. The imprint of a historian's eye is seen throughout the set and story lines of LOST. Perhaps, it was all Ben's heavenly diversion.
He could have been rewarded in the after life limbo we call the sideways realm with the opportunity to "live" an alternative life. He chose the opposite of his boring school teacher existence; he wanted to live the breathtaking levels of history. And he wanted to share the experience with people around him, such as Arzt, Rousseau and Alex. But at some point, Ben's emotions got ahead of his rational mind and caused many people collateral pain. It was coming to terms with that fictional but seemingly real collateral pain is why Ben decided not to move on with Hurley.
Could the island events been the captive imagination of after life Ben? No, because the Ben character was never the starting point of the series. But since the series made so many strange twists and turns to lose its original direction, it is possible that the events were the post-death fantasies of a character like Ben.
