I think most people pick up memoir because they want to empathize with the protagonist, apply lessons learned to their own life AND be entertained.

That's not to say there is no such thing as memoir written purely for entertainment purposes. I can think of a few that I have read, but it occurs to me every example I can think of is a book that did not sell well unless the author became famous later for other reasons.

On the other hand, nearly every best selling memoir I can think of has some sort of story goal, climax and resolution to the story with a lesson learned (i.e. narrative structure).