I'd fully expect "11 reasons people speak at conferences" to include a lot of reasons associated with personal benefits. (And I'd actually only count 3 of those as being vanity: the rush, promotion, and recognition.)

People sure don't speak at conferences so they can spend more time at airports and on planes.

Many do also enjoy it for altruistic reasons listed. But relatively few people are going to take on tasks that aren't also beneficial to themselves personally.