I imagine that you'll immediately dismiss me as evil, or, more condescendingly, as "uninformed" - but the reason I support long prison sentences - life without parole, in fact - for crimes like murder or rape - is not to rehabilitate, it's to prevent those people from ever murdering or raping another innocent person. As long as they never leave prison, everyone outside of prison is safe from them. And for me, that's the critical thing, to keep society safe from proven murderers and rapists.

After that overwhelming priority, I also feel it is morally obligatory that people who murder or rape suffer for what they did. If someone purposefully takes or ruins a life (via rape), then it is morally wrong for them to have a decent life after that. I imagine you disagree - I suggest reading this: https://en.wikipedia.org/wiki/Murder_of_Junko_Furuta

And then tell me if you still think that rapists and murderers deserve to live a happy life ever again after what they did.

I also don't believe that it's worth spending a dime rehabilitating serious criminals - the odds of success are too low and society can better spend its attention on fixing the problems that lead some people to become criminals (not all people, of course, and not all criminals either - some people are incredibly evil without environmental influence).

Finally, the evidence I've read suggests that deterrence does in fact work, albeit not as much as I'd like. But that comes last in my order of priorities.