Picower may have figured out it was a Ponzi and agreed to "invest" in the scheme when Madoff became desperate for liquidity. But there was plausible deniability as he was just a guy who bought in at times and sold off at others.

So maybe the actual trick is people like Picower, who identify these schemes and then leverage the scheme to their advantage while all along looking like another victim and never once speaking about their suspicions or getting involved in the mechanics. Which brings me to think perhaps the Picowers in SBF's scheme were some of his investors who figured out it was a scheme but believed they could cash out before it toppled.