People bought caffeine off campus because it wasn't available on campus. But if it would have been available, they would have preferred to have it closer - in the dorm, in the wilk, etc...

The poll asks whether folks would have bought it if it was available on campus, and the result seems to say yes. The fact that people actually did and do buy it where it is available from competitors seems to confirm that they would act according to their votes.

It's like if Apple asks its customers, do you want larger screens on the iPhone, and people mostly say yes. At the same time, Apple notices that they're losing a good amount of customers to Samsung etc... and their data shows that part of the reason is the larger screen sizes. That would indicate that there's a demand among apple customers for a larger screen size.

I'm not an economist. I don't really know the correct phrasing to use. But it seems to make sense to me.