I don't really get these things... why code all night when you could just as easily code all day without entirely throwing off your biorhythms and feeling like crap the next day? It seems to me that I'd be a lot more productive when I didn't feel like burying my forehead in the desk (see 9:15 AM).

Berkeley's hackathons are every six months, and given the way undergrads generally sleep, I don't feel like this is a huge deal.

That said, the main pros are probably the camaraderie and the challenge. The general case is people coding (long term projects) during the day and sleeping at night. Hackdays are different and fun! Plus there were prizes.

Full disclosure: I was a judge. Trevor Blackwell (from yc/anybots) was too.

My career path might have taken some much more interesting twists when I was at Berkeley... I never discovered a hackathon happening then with punch-cards.