Sounds like you have a fun opportunity lined up. I would personally try to broaden your message some. Kids get told what they should do all the time. I would t

Sounds like you have a fun opportunity lined up. I would personally try to broaden your message some. Kids get told what they should do all the time. I would tell them that one of life's true joys is to find something you love and to spend your life working on it. Then you could segue into a discussion of how hacking has been a personal source of meaning for you. Talk about the points you mention above, and then bring it full circle by telling them that any road they walk down can be equally fulfilling if they find something they truly care for: life's value derives from what we do, not what we have. Hope your talk goes well, and keep in mind there is probably a reason you are being asked to give a talk and not me. ;)