They present themselves just like a ponzi
No, they don't. You think so.
Please elaborate, why don't you think they are a ponzi?
I don't know, but there is a chance that these guys know what they are doing, isn't it?
I noticed that it is very difficult to launch a new service, because people do not trust anything. Even new legitimate exchanges suffer from this. But among them there are many good services, so why not give them a chance? Nobody says that you should give them all your money, just enough to treat them more kindly.