I can't say I know every detail of the case but I don't recall anyone getting killed or even hurt by Mr. Ulbricht so in my mind the punishment does not fit the crime. IMHO the death penalty should be off the table completely (go Nebraska!) and life in prison reserved for only violent offenders. You can argue that he enabled people to harm themselves but I think that's stretching it. If people want to take drugs, even take too much drugs their going to get it somewhere. If drugs were legal and treatment of abuse the focus instead of punishment Silk Road wouldn't have existed in the first place.
The prosecution brought this up at trial but he was not charged or convicted of this in the criminal trial.
"As explained above, the murder-for-hire evidence is probative both as evidence of the charged offenses and to prove Ulbricht’s identity as DPR—a key disputed issue in this case. In addition, the charges in this case are extremely serious: Ulbricht is charged not with participating in a run-of-the-mill drug distribution conspiracy, but with designing and operating an online criminal enterprise of enormous scope, worldwide reach, and capacity to generate tens of millions of dollars in commissions."