Like it or hate it, this is what the SEC does. You think Martha Stewart deserved jail time for making 50k in an insider trading scheme she didn't really care about?
The SEC finds very public cases and then brings the hammer down in order to act a deterrent. Martin Shkreli broke the law, something he didn't have to do. It isn't like it was mob justice and some hugely biased jury convicted him of all the crimes he was committed of without thought. The jury by all accounts fairly deliberated his actions and convicted him of crimes that he did, while letting him off for crimes he didn't do.
Then all Shkreli had to do was show some remorese and kiss the ring a little bit, but he continued to be a troll and mock the justice system. He downplayed his crimes literally minutes after being convicted of them, which showed a lack of remorse (and maybe honestly so, but the justice system doesn't like that). He continued to be a troll, including the whole Hillary Clinton incident, many of these statements used against him in sentencing.
This isn't a case of the tall blades of grass getting cut first. It's a case where we have a subjective justice system that doesn't want to be mocked while it is doing it's job. Shkreli went out of his way to mock it, he went out of his way to mock the SEC, all the while he actually did commit a crime. Yes, it is a witch hunt in that the SEC will throw the book at some people while letting other people who committed worse crimes off the hook (Phil Mickelson vs Martha Stewart), but that how any limited investigative body works. If you don't want to be a target of a witch hunt, don't break the law. And if you do, kiss the ring. I'm not convinced it is a huge indictment of our society that people who break the law all the while trolling everybody get unfairly harsh punishments, though I admit it is unfair in the sense that life as a whole is unfair.