Is it benefitting Society?

This definately is a controversial issue as it can be tied to many surrounding issues and concepts. a major concern is that fact that keeping a prisoner alive in a prison is very costly. The average dollar value for keeping one prisoner alive, feeding him and making sure there is a bed for them is 36000$ a year. And thats just one inmate. Now in the united states there are approxiamtely 2.5 million people incarcerated. You do the math. Do you think we could better society with more extensive social programs with that money or is it justifying its cause by keeping a killer or a rapist alive?