As for profiting ponzis - this is not that. He could not have possibly made 21 coins by using the website.
This is profiting from the trades on a free market. Do you have moral problems with that too? Remember, there are people who buy what you sell! lol
GAW and paycoin are likely ponzis. There is nothing wrong with investing , trading and profiting but doing so within a ponzi is unethical.
I've often wondered, who's worse the ponzi designer himself or those who knowingly invest and promote said ponzi allowing the ponzi to last even longer bringing down even more victims.
Yeah, that's partly the reason why I don't participate in any cloud mining stuff.
But please separate the 2 things.
PayCoin is an altcoin which I trade on the exchanges - That's not a ponzi, it's trading.
Altcoins come and go. Devs scam or legitly fail. Some succeed. You get lucky. More often you get f*kd. You do your homework, you get f*ked less. That's how it is.