It doesn't sound like they have been to very many. The majority of the people at a hackathon actually go home at night. Quite a few don't even stay the full day. It's perfectly OK. I used to stay from Friday night to Sunday night coding the whole time at the longer events like Startup Weekend, but after I got married I go home for few hours each night at the wife's request. No one has complained.

I don't think most people expect to win either. For most it is just a fun way to try out APIs or other ideas and work with friends and make new friends. It's typically very easy to grab something like three.js, the Uber API, Meteor, etc. and hack on it all weekend and then if you want to integrate it into your real project later you'll see that you learned a lot hacking. I've picked up lots of new coworkers from hackathons too, so it is valuable for recruiting.

The value of the hackathon is not the prize money times your chance of winning it minus the time spent. You can benefit from the hackathon even if you don't win. With their current attitude, I don't think the author could benefit from going, however.