Or set one up called "Free WiFi" in a location with a WiFi blackspot that many students congregate at.

There is no profit though, no one uses YikYak for posting anything remotely important.

Don't take it so literally. In this case "profit" is just synonym for "goal".

See: http://knowyourmeme.com/memes/profit

Ehh, people sometimes post embarassing/hateful things on YikYak, being able to out them would be a problem.

Or to blackmail them so you don't reveal their identity.

An app should not be considered "secure" because it doesn't currently have important data.

Twitter wasn't much of a honeypot, either, until activists and corporations started using it. Did Twitter know the exact moment that happened? No. They should have been secure long before that.

There's this thing called a "jasager" that you might also be interested in looking into. Particularly combined with airdrop-ng. I was a bit shocked when I learned how that particular aspect of 802.11 is implemented.