You misunderstood, these users are not rewarded for their posts in this thread. They post reports about received remunerations in HYIP projects, in which they participate. Also rewards from Profit-Hunters BIZ project for participation in various quizzes, referral rewards and rewards received in various bounties. Thus, they confirm that these projects are not some kind of scams, but normally working projects where you can earn money.
Pretty obvious its a requirement that they post their "earnings" in the thread or they wouldn't waste the time. So its part of the job, like a bounty hunter except with lower pay. Whole thread should be nuked for paid posting.