revenge

It's stories like this that can make people feel like the only people they can trust are themselves. This guy was borrowing money from tons of people, with what would seem to be no genuine intention of actually paying them back. Unfortunately, this guy's tactics didn't get the guy to reconsider his approach to life and finances. Oh well. 

The only good thing about having a roommate that steals your stuff is that if you tamper with your own stuff, they're in no position to complain about your stuff that they deny taking. This is a pretty common tactic. A similar and more explosive thing happened when this food thief's roommate switched to regular milk.