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.