The keyword is stealing, that's why the man is punished by the Chinese government.
And yeah, maybe 'greed' also is a factor, he wanted to mined more bitcoin that he is capable with, and well his re-course is to take advantage but unfortunately, he was caught and sentence to 3.5 years. It is worth it? No, what he did is really against the law and is punishable. And I'm sure he once he get out, he will go back to crypto but I don't know if he is going to solo mine or not at the difficulty will go up 2020 plus he needs to buy new model of mining hardware.