I have been in the hospital and have seen this happen. It's sad, when someone who is sick gets out simply because they're not suicidal or homicidal. There is still the fact that they need help, but they often let these types of patients out in order to make room for future patients who are suicidal/homicidal.

What bothers me is the lack of outpatient care given to them. Your friend definitely sounds like they need outpatient help, but is not getting any. This, to me, is wrong.

I don't think the family can do anything to keep him in, unless it's proven that your friend can't make proper judgements for himself, or he becomes a harm to himself or others.

I hope your friend gets the help he deserves.