Not for them. I want to improve the world by facilitating various things. For example, I want people to write more and better IMAP clients and use webmail less, so I answer IMAP questions. As it happens I know a lot about IMAP, and put that knowledge to use in a small way.
SO's business model is to make a profit by helping me do such things, and helping others do similarish things. That's a good way to earn a living.
I get it. You love to share the knowledge, help along the way and learn new things. I've never thought about SO on that way.
Writing software that boosts positive behaviour within a community is devilishly difficult IMNSHO. Those who do it deserve all they earn.