Sure. They lure you in by giving you cheap gifts. Once you get those gifts, you begin to get addicted, thereby striving to earn the most points in order to get the biggest prizes. Forget the small stuff they gave you in order to gain your loyalty, you're aiming for the top tier now. Because of this addiction for "free prizes", their clients will continually get more and more impressions, day after day, week after week, and month after month. In other words, they're getting more in return then you are. Do I doubt some will get these "large prizes"? I'm sure they will - and they'll spread the news like a ravaging wildfire, but the majority will not.
I'm also willing to bet the majority of points comes from the referral of new members. These new members in turn, will attempt to gain more new members. The scheme continues on, therefore becoming a simple pyramid scheme.