4 + x + 2 + y
Mentorship is an integral part of hackathons. It is where hackers meet and learn from veterans in the field. Mentors get to groom the adolescent and share their experience with the hackers. After all, how many times have we said "If only I tell my younger self.."
Besides, the student hackers now, will be peers later. And would it not be better if bad practices were nipped in the bud? Imagine this, a young developer learns to use spaces instead of tabs and he would not have to unlearn the horror of tabs!
Furthermore, you're never too old to learn. Maybe the freshers give you a new perspective on an old problem. Hackathons are melting pots of ideas and hacks. You never know where you find inspiration!