He certainly committed fraud, but it’s certainly unusual that he was prosecuted for it when nobody lost money. In fact, investors did well.

It’s hard not to feel like this is not a thing that would have been investigated had he not been a totally raging asshole.

It’s not true that nobody lost money in spite of the fact that he made this claim in court and it is repeated frequently. The court found he reduced the gains from group A to pay off losses from group B. People in group A lost money that was rightfully theirs as a result of his actions.

"On December 17, 2015, Shkreli was arrested by the FBI after a federal indictment in the U.S. District Court for the Eastern District of New York was filed, charging him with securities fraud. The charges were filed after an investigation into his tenure at MSMB Capital Management and Retrophin. U.S. Attorney Robert Capers said, "Shkreli essentially ran his company like a Ponzi scheme where he used each subsequent company to pay off defrauded investors from the prior company."

Justice Department press releases are incredibly biased. His hedge fund failed (legal), he lied to his investors and said everything was fine (this is the fraud part), then he started a drug company called Retrophin (now NASDAQ: TVTX) which ended up being worth a billion dollars and he was able to repay investors in shares of Retrophin or proceeds from selling shares in Retrophin.

I think that is a misleading quote. He made actual profits, albeit by unscrupulous (but legal and very common) methods. There was nothing like a ponzi scheme, the prosecution just wanted to say a crime that was well known at the time. Along the way he made false statements to investors, and he was so gross and unpopular they were able to get a conviction the "victims" were not even interested in, but only on two securities technicalities and only because the jury wanted to get him on something. He was acquitted of 5 other more serious charges.

This is a great example of a public show trial, where they basically make an example of someone while allowing companies to engage in the same disgusting behavior without any attempt to discourage it.