How can a person get 20 years in prison when they stole from criminals?

Related to this story about James Zhong [https://www.bbc.co.uk/news/technology-63547765](https://www.bbc.co.uk/news/technology-63547765), he stole 50,676 Bitcoin from silk road and faces a possible 20 year sentence. This was a non-violent theft from people who are considered criminals (sellers on silk road), I don't see how the sentencing would be justified?