I think bitcoin is not like ponzi and bitcoin schemes are more likely to be digital currencies in general, there is no ponzi in bitcoin, bitcoin is a digital currency chain that does not implement profit referrals, it is only the result of several markets that provide referrals like that .
of course not. we know some people do use bitcoin to commit fraud, and well, I've also been hit with their tricks several times. but, I think, most of that is not a scam. I am sure, if you have followed the path, then you will know the scam or not.