the ponzies are OK if you wanna "play". you can earn money, you may lose....BUT at least you are aware of what you are doing.
Example: if you think that the cloud mining is a real business and you put all your earning in a cloud mining, then you can expect (99%) to be burned.
Play how much you can afford to lose and it's alright
Also, there are normal ponzies (HYIPs) here:
http://www.talkgold.com/forum/f261-.html . Most of them are using BTC too.