I actually am planning on giving away something of value to every person who signs up under my referral link on every Conga I'm a part of, when my turns come around. Others are too. Just because a couple people are giving away less enticing prizes doesn't mean everyone is.
Also, I just realized something regarding the longevity of these offers. I imagine Trainn's business model factors in the probability of these taking a long time to complete (and of course, for many people to complete offers and never get enough referrals). If they drag it out for a couple years, the consoles will see price drops. In that scenario, if someone opts for the console instead of the cash/GC, Trainn can pocket the difference, in addition to interest they've been collecting on the money already earned. If you're wondering why I brought this up, I searched for some older console Conga lines on other fora and found some people who signed up for PS3s and finally got them 2+ years later.