People who have no grip on reality need to be kindly locked up. Otherwise they are repeat victims of crime as well as offenders.
I've read that before, but this article disputes the latter part:
"In spite of the sometimes frightening behavior, people with schizophrenia are no more likely to behave violently than are those in the general population.In spite of the sometimes frightening behavior, people with schizophrenia are no more likely to behave violently than are those in the general population. "
http://health.nytimes.com/health/guides/disease/schizophrenia/complications.html
Then of course we have the question of whether we want to lock up all individuals who belong to any class that has a crime rate high enough above the average. I say no, the government must treat its citizens as individuals.
Referring to another example I made, I would not just lock up someone who wears a Hell's Angels jacket, even though he belongs to a group that has a far higher than average crime rate. The particular Hell's Angel jacket wearer would have to commit a crime first.
As your point that psychotics are more likely to be victims of crime and therefore should be locked up, I would propose that we lock up the offenders rather than the victims of assault and theft.
“Some 28% of those with both schizophrenia and substance abuse were convicted of violent crime, compared to 8% of those with schizophrenia and no substance abuse, and 5% of the general population.”
http://www.irishhealth.com/article.html?id=15563
My reason, though, for desiring the kind institutionalization (NOT the punitive imprisonment) of severely crazy people is not simply to prevent crime.
It is a kindness to them. They are dependent and helpless.
Just as I “forcibly” detain and shelter and care for my kids, or we “forcibly” detain and shelter and care for the senile and demented, and the severely mentally impaired -
we need to do so for the crazy. They are just as needy of sane adult supervision.