I don't know exactly, but of what use is prison in this case besides inflicting unnecessary suffering? There probably is no hand-wavy answer to this, but surely it is possible to come up with sufficient civic restrictions on him to prevent him from committing similar types of crimes. For instance, there is a precedent for restricting a person's access to digital technology. Even house arrest is way more humane (and probably also an overkill).
Theft and fraud on this scale is absolutely violence in some sense. Don't assume everyone that lost money could afford to lose it. The second order consequences of this fraud are likely severe.
Putting him in prison, ostensibly, makes it less likely for someone to want to do what he did. You know, the whole "repercussions" thing? After all, if you stole a billion dollars and all they did was prohibit you from using a computer, why not try?
I cannot agree that deterring others from undesirable behavior is an ethically valid reason to punish anyone. People don't break laws 'just because'. Behind every crime there is always a smorgasbord of neurological, sociological, economic, etc. reasons - these include white collar crime such as financial fraud [0]. Unless we assume the existence of libertarian free will (which we shouldn't), a 'choice' one makes to commit a crime is simply an illusion. If it is an illusion, and our hypothetical crime was not a real free choice on behalf of the criminal, what are they punished for, besides being in the wrong body in the wrong time?
In the majority of world's societies, including US, prison systems are a horrific environment filled with violence, rape, drug abuse and dehumanasing living conditions, which inflicts to the inmates the lifetime of trauma. While at the moment there are no better solutions to isolate truly violent and antisocial people (recurring murderers, gang members, and others - those who simply need to be separated from society)[1], throwing anyone in prison should always be the absolutely last resort, preceded by rehabilitation programs and psychiatric treatment. Throwing people in prison to deter others is ethically identical to chopping away the hands of market thieves - a measure that, while somewhat too barbaric for the modern era, follows exactly the same idea.
[0] - for example, many children, especially from middle- and upper-class backgrounds, are conditioned to 'succeed' at all costs; they often adopt cheating as a strategy early in life - not because they are inherently bad people, but as an adaptation to the constant pressure to be good enough for their environment.
[1] - in fact, the real problem is that people who commit these crimes receive no compassion from society and are universally agreed to be deserving to be treated like absolute scum. If we ever manage to reach a civilized future (which humanity might not deserve), our current methods of dealing with criminals will rightfully be compared to the treatment of people with leprosy in the medieval times - barbaric and evil, but they simply didn't know better then.
Who said they do? And this is the basis of your entire argument?
> Behind every crime there is always a smorgasbord of neurological, sociological, economic, etc. reasons - these include white collar crime such as financial fraud [0]
Who said that's true behind every crime? You don't think there are crimes that aren't the result of social conditions? What were the social conditions justifying SBF' lies and theft?