As a purely hypothetical argument, there's a net benefit to society if someone's productive efforts go into stealing from or otherwise harming other people. How many people fall into that category versus how many can be reformed or otherwise kept from causing harm is something I don't have facts about and is probably another debate for another site.

Whether there is a "net benefit" depends on how much time they're in prison for, how much harm they caused before going in, and what kind of good they do/value they contribute once they're out. Even after the time it would take to establish an effective metric, that's something that would vary very widely by individual.