How many people have actually reached profit zone using Bitcoin trader?
Probably hundreds did. Consider that just a fraction of their customers is participating in public forums and they are in their 3rd 120 day cycle now.
So how can this be a ponzi then? What kind of ponzi lets hundreds of its users to make money?
?? If this is a ponzi a users make money, this means that ponzi loses money.
Just does not fit.
It fits perfectly. In fact, paying out properly, at least at the start, is one of the main characteristics of a Ponzi scheme. Otherwise it'd just be a simple grab-and-run scam. As long as more new deposits come in than is withdrawn, the Ponzi-operator has an incentive to keep the operation running. The longer the operation runs and successfully pays out, the more confidence people gain in it. If many investors decide to not withdraw their money and instead leave it on the site (perhaps doing one or two test-withdrawals to ensure that that works), it doesn't require many new deposits to keep the scheme running.
However, since no actual profits are being made, at some point the scheme will grow to such a size that the amount of withdrawals starts to outpace the deposits. At this point the operator typically closes up shop, sometimes with a coverstory like the site being hacked, sometimes they just go offline without saying anything.
Ultimately, the question "do they pay out?" is an extremely poor way to decide whether something is a Ponzi scheme or not. However, Ponzi-promotors typically use this as their main argument to convince people to invest. Much better indicators are whether the organization is transparent (BT: nope), whether the profits they claim are realistic (BT: nope), whether there are no inconsistencies in their story (BT: nope), whether it makes sense that the company seeks small investments from consumers rather than VCs (BT: nope). These points are all red flags you can use to evaluate these types of operations.
The 120 day maturation period that BT uses is a clever innovation for Ponzi schemes. It serves a dual purpose. First of all, it makes the story more believable (An investment shouldn't just allow you to withdraw any amount of money at a moments notice, since your money actually has to be doing something in order to generate a profit). Secondly, it gives the operator a good picture of when possible peaks in withdrawals can be expected. Many Ponzi schemes collapse when a bankrun is started from panic due to unexpected downtime or the Ponzi being revealed. With the 120 day lockin period, people can't mass panic and withdraw.
Nevertheless, despite this clever innovation, there are more than enough red flags regarding BT to make you not want to touch it with a 10ft pole.