Since I don't live in a MMJ state, but I care about making cannabis available to those who need it, including legal users in a nearby area, I can't really answer fully.

But my purpose is to provide access to genetics, as well as tech support, for MMJ users. It doesn't pay well, haha. I cover my electric costs, that's about it.

The reward is multi-fold:
See someone empower himself by growing his own medicine.
Cut the street-level-dealer BS out of the picture.
See well-bred lines being used to their potential to treat illness.
Promote self-sufficiency.
Satisfy my own desire to teach people a new skill.