Many of the students that wanted to go into startups after graduation instead of a job either had started on some product during school and wanted to see that through to completion, or were of the mind that they could just work for a few years at {Amazon, Google, Microsoft, ...} and then do the risky thing.
There is also a lack of exposure in the curriculum. They are in the middle of re-designing it, but before that only one class let you create a small team, come up with a product, and build it. It was seen as a painful course (it was) and it was also taken by most everyone (including people who couldn't care less, so it was hard to find a group of 4-5 motivated people). I don't recall any hackathons when I was there aside from ACM programming competitions.
