The greed is usually some form of "buy this product and you'll become more successful".
The fear is usually some form of "don't buy this product and you'll lose your job."
My question for you is:
The correct answer is Fear.
Human beings are much more motivated to avoid pain than to seek out pleasure. Because of that, fear has much more power to motivate than greed, or indeed any other emotion that's connected with pleasure.
According to high tech guru Geoffrey Moore, some B2B vendors are motivating customers to buy (even during hard times) by identifying something that terrifies them and then developing a sales pitch that explains the horror in an insightful, actionable way. He cites the example of the software vendor Sybase, which was able throughout the summer of 2008 to pry business out of financial services clients, even as their industry was beginning to implode.
He recommends not just playing to the fears that the customer already has, but instead creating additional fear of things that aren't yet worried about. The more nameless and horrifying the fear (like the collapse of the entire banking industry), the more likely it is to motivate. In fact, if you can scare your customer badly enough, they'll buy almost anything. At least that's what Moore seems to think.
This is not to say that I'm recommending this approach. Personally, the idea leaves a bad taste in my mouth. And, in my view, if you scare a customer too much, you could end up with a deer-in-the-headlights reaction that actually prevents buying behavior.
However, it seems to me that motivating people by scaring their pants off isn't really all that different than motivating them by making their mouths water. It's kind of manipulative in either case.
READERS: I'm interested in what's worked for you. Do you use fear to motivate buying? And how does that work for you?