People learn to share.
Thanks for the question. I think, an initial stimuli of almost all of our actions and activities are emotional — either gaining or loosing a status in the group.
As the mouse, that fears of electrical shock so it keeps its paws on a lever, we keep learning bacause we fear to loose the status in the eyes of our friends, relatives, and colleagues.
The great example is the Duolingo energy charts, I try to keep them full and green:)
Oppose to the fear, the possitive reinforcement triggers more positive emotions, associeted with the achivments, e.g. “Golden Card” or “Elite Author”.
In a e-learning industry, it could be a status of “expert”, “guru” or “great artist”, that people are to seek. To achieve this status, people always share what they learn.
That cause such social sharing platforms like Medium or Behance to strive.