I'm confident that if you were to analyze when you torrent vs. when you buy, you'd notice trends that, with a bit of effort, could be translated into a fairly reasonable "Will I Torrent or Buy?" function that predicts whether you'll torrent or not with much better accuracy than random.

Yes, but the function might all include terms for things like how rude were Yvain's co-workers to Yvain that day, what mood was Yvain in that day, was Yvain hungry at the moment, i.e., stuff a reasonably behaved utility function shouldn't have terms for but the outcome of a willpower based struggle very well might.