alt Hacker NewsI can't tell if you're being deliberately obtuse / sarcastic, but even aside from the ethical considerations here, prison is an insanely expensive way of dealing with the issue.
In the US in 2010, cost per inmate per year in a state prison ranges between $14,603 (Kentucky) and $60,076 (New York), and averages at $31,286. That's 16 years ago, so it'll be higher now. In the UK it was an average of £32,315 in 2020-21. You might as well employ an individual case worker, and the societal outcomes would be a hell of lot better.
I was quoted a figure of approx. £200,000 per year for each patient at the Royal Edinburgh Hospital by someone who works there but I can't vouch for it. I know someone who has been in there a year. :( Carstairs, where violent psychiatric patients go, is probably even more.