He did kill people. That factored into his sentencing[0]: the multiple overdose deaths from heroin and other things Ulbricht sold/facilitated/took a cut of the proceeds of.
He killed children.
- "During the sentencing hearing, Forrest heard from the father of a 25-year-old Boston man who died of a heroin overdose and the mother of a 16-year-old Australian who took a drug designed to mimic LSD at a post-prom party and then jumped off a balcony to his death. Prosecutors said the two victims were among at least six who died after taking drugs that were bought through Silk Road."
[0] https://www.bloomberg.com/news/articles/2015-05-29/silk-road... ("Silk Road Mastermind Handed Life in Prison for Drug Bazaar" (2015))
It's squarely within the Overton window to impose extremely harsh sentences for people who sell heroin*. Most (?) Asian countries *execute* people who sell heroin. Trump himself has proposed, multiple times over the years, executing US heroin dealers[1,2]—which underscores the incredible degree of hypocrisy behind this pardon.
*(It's also within some people's Overton windows to contemplate the opposite of this, in a framework of harm minimization. I can't steelman this argument in the specific case of Ulbricht. Is it harm reduction to sell heroin? Is it harm reduction to sell fatal drugs to high-school age kids?)
[1] https://www.bbc.com/news/world-us-canada-43465229 ("Trump urges death penalty for drug dealers" (2018))
[2] https://www.npr.org/2023/05/10/1152847242/trump-campaign-exe... ("Trump wants the death penalty for drug dealers. Here's why that probably won't happen" (2023))