Please don't distort the record. He committed a crime (defrauding investors) which carried potential prison time as a sentence. Prosecutors sought 15 years. The judge sentenced him to just 7. Considering he displayed disdain for the law and showed little hope for reform, putting him away for 7 years seemed reasonable to the judge, as he would have likely committed more crimes had he gotten off with a wrist slap.
https://www.nytimes.com/2018/03/09/business/martin-shkreli-s...