1. misleading the American public into going to a series of costly wars through lies about WMDs -> not punishable
2. Weakening Glass-Stegal and encouraging questionable and irresponsible risk-taking at major banking institutions -> not punishable
3. Fraudulent evaluation of risk-ratings by trusted agencies for the sake of profit leading to worst financial disaster since great depression -> not punishable, actually, rewarded with billions in bail-out by tax payers
4. setting up and running a website to host underground drug trade with bitcoins -> punishable by life-sentence
Not that what Ulbricht did was right or that he shouldn't be punished... but his biggest problem was that his business didn't generate enough profit at the expense of the public. Justice might be blind, but even she can still smell money.
5. Apples are red
6. Oranges are orange
You're comparing facts: "Ulbricht ran The Silk Road," with your own conjecture: "Banks encouraged 'questionable' risk taking." You're making a lot of extraordinary claims that are very very difficult to prove with no evidence to back them up.
And you're using this conjecture as evidence of... something? You don't really make a point. You just repeat popular internet tropes.
When people that have clearly violated the law - like certain people in the CIA, for example - are not even prosecuted, it is hard agree with people that think it is "just" to give someone life in prison for allegedly committing as far lesser crime.
At worst, Ross Ulbricht is accused of an attempted conspiracy of murder. People in the CIA actually killed people, in ways that are always illegal.