You're talking about other people's motivations. But DJB minus ego wouldn't be some other person, he'd still be DJB; just "DJB if you cut a certain part of his brain out." And I don't think that that person would have any other motivation-generating part of his brain left. His works specifically seem entirely ego-driven. DJB minus the ego probably wouldn't have had any interest in becoming an information-worker at all. (I'd like to think he'd become a janitor, like the protagonist of Flowers for Algernon. :P)