I'm pretty sure the "no harm no foul" defense doesn't hold water in a fraud case. A Ponzi scheme is illegal the entire time (because it's fraudulent) even though the early investors receive returns.
In Shkreli's case, he didn't actually harm anyone through fraud, because although he committed fraud, he got them their money back through entirely legal, non-fraudulent means.
Completely over the top illustrative example: you give me money for ten years to invest in real estate, because your investment portfolio is lacking in that sector. I blow it all on cocaine and hookers, then when the money is due I get nervous, buy lottery tickets and win. You get your money back, with a nice profit attached in the upper parts of what could be expected by a real estate investment. Was I a faithful manager of your money? Hell no! If you wanted lottery tickets you would have bought them yourself.