The comment by Graham Seiner on the article "Given that the newbie devs all go to Stack Overflow to get questions answered, this makes sense. The real question

The comment by Graham Seiner on the article "Given that the newbie devs all go to Stack Overflow to get questions answered, this makes sense. The real question is what do the older hackers get out of answering all those questions? Seems like that's the secret sauce to a vibrant community." is the real question. Do you have thoughts on what brings older hackers back to teach younger ones?