I would never condone the death penalty. The idea that they should be able to take there own life if they wish has some merit. The one problem I can see is that you're then giving them a way out of a long prison sentence and giving them the choice. There may be some who think that is unacceptable.
Prison in general isn't a simple option, particularly with shorter sentences. For some it's a wakeup call which leads them to avoid offending again whilst for others it's just something they go through before carrying on as before. If you've got a family and /or a lot of friends and you enjoy going out, then even a short stay in prison won't be fun. If you're on your own, lonely, possibly homeless and sleeping in a shop doorway every night then it's probably not that bad and may be preferable.
For longer sentences, such as in this case you may well just get used to it, as how and where you live.
People are different and come from different environments. A 3 bedroom house with a small garden and a 3 week holiday a year with social events for the rest is fine for many people. A multibillionaire or a keen mountain climber, explorer, ect might consider it a prison. Many people who are famous find the same problem.
It's not a simple issue and I don't think money should be the main consideration.