Once again you are being very vague, to really address the issue you need to maybe cite a specific case. And delusion doesn't seem to be grounds for Involuntary commitment. Personally I find those who believe in a god and talk to him regularly are incredibly delusional. Should those people be locked away, or because this delusion is so commonly shared, is this why it is considered OK. And as for feelings of paranoia and being watched, their are legitimate concerns for this in our modern society that is now heavily littered with CCTV's, Internet activity being watched and illegal phone taps being regularly used. Same with the water, it has been fluoridated for a long time, and depending on what research you want to believe, it may not be such a good thing for human health. This types of issues when they become distressing speak volumes about the patients feeling of having little control over their environment and little to no choice in such matters. These issues are of great importance in the scheme of existential questioning. I am not saying those claiming they are being watched or spied on are correct or not delusional, but their thinking is based on some truth. There are plenty of things that need to be explored deeply to get to the root of it, simply dismissing people as crazy because you don't understand what they are trying to communicate is a big part of the problem.
And often those who are institutionalised do whatever it takes to get out, so they learn to play the game and tell the Psychiatrist what they want to hear. If they commit a crime they should be afforded due process like anybody else. To be locked away for talking nonsense to themselves is a crime. Like I said, if talking nonsense to ones self was a mental illness, the majority of the worlds religious people would have to be locked up. It never occurs to the powers that be that the so called mentally ill person is displaying a normal reaction to being overpowered with force, held and drugged against their will and not given due process in regards to their involuntary incarceration. You attempt this type of display of power with any so called normal person and watch them meltdown dramatically. Let me judge you mentally unwell and then force-you at gunpoint away from your home, deliver you handcuffed into a psyche ward, strap you to a restraint bed and then drug you up if you don't comply with my diagnosis and then hold you indefinitely. I guarantee I could have you babbling bullshit to yourself by the end of the day.
Ok, let me clarify one thing; people will not be locked up against their will for simply having delusions or hallucinations. They HAVE to engage in either self harming behavior or be violent/dangerous to others in order to be locked up against there will. We have even send patients home untreated because they like the voices in their head (a guy heard five girls talk to him the whole day long for example which he found pleasant and didnt make him engage in behavior which is forbidden by the law).
Let me then describe you a case;
Paranoid schizofrenic woman has been admitted over 30+ times. Always the same story; the neighbours break in, she has poisoning delusions, smells gass everywhere. The woman has moved a gazillion amount of times yet these ''problems'' always come back. When things get so bad she usually try's to burn the neighbours house down or something like that and gets brought in by the cops.
The first few days she's completely out of it; cant differentiate night and day thinks everyone is telling lies when we say its 8am or something. She has smelling hallucinations; smells gas and dead bodies everywhere (let me assure you, there are no gas leaks and no dead bodies in the department). She doesn't trust anyone thinks people are going to poison her; food water etc (even though that hasnt happened the past 30 stays at the hospital). She has strange body sensations; thinks people can control her hands (haha try rationalizing that one).
Anyways the dangerous behavior continues and she gets forced medication (because she refuses pills). A good week later she doesnt have ANY of the above described symptomns anymore is super relaxed leaves the department during the day and comes back. Week later is fired from the hospital and continues life. This will go all good for a month or three untill she stops medication (she thinks they are not necessary) and the cycle starts over.
Ofcourse this is an extreme case of a chronic patient who will never have insight to her own sickness. There are people who have one psychotic episode and realise they will need the meds for life when they are better. Those live a happy life and will not be found in a clinique anymore.