Very interesting thread.
I can come at this from a few angles because it is a topic that interests me greatly.
Over the weekend due to general boredom I did what they call a "deep dive" into the whole Wayfair thing - I scoured Youtube and a few of the better known conspiracy forums. When Pizzagate was a thing, I didn't look too closely because it seemed so bonkers, but the way the new one exploded had me intrigued. What I concluded is that in amongst the most outlandish dot joining, there is evidence of things that should, in my opinion be investigated - CSA is a thing and there is no reason to believe that rings don't exist at higher levels of society - in fact, it has been proven and people have been prosecuted - and cover-ups have been exposed. people with power and money can manipulate others - blackmail and threats have been used on police officers and other people who have tried to expose it all.
Sadly, all the theatrics around "The Illuminati" and "Satanism" encourage polarised views and this harms the children involved - as I said on another related thread, it's not beyond possibility that some unhinged perverts have used such subjects as a backdrop to their activities, but because we can't fathom doing something that awful, such accounts can be dismissed as fantasy - ergo, if the one thing is deemed false why should the other part of the accusation be given credibility?
It's a very fraught area.
Other posters have pointed out that the deeply religious are not generally regarded as mentally ill, yet hold beliefs in things that we feel are delusional.
I can tell you that paranoia during psychosis is most bizarre and very troubling, because when I was 42 I suffered a drug induced psychosis when my areshole ex spiked my tea with weed. I didn't do any sort of non-prescription drug then, and he did it because bizarrely, I had an adverse euphoric reaction to anti-depressants and instead of gently guiding me back to the GP when I started hugging trees and talking to squirrels he thought he'd "calm me down" himself. When I discovered what he'd done, it triggered a massive breakdown and I ended up sectioned for 28 days. We'd been married for 14 years, he was manipulative and controlling and I had experienced trauma in my life that had never been properly addressed. It was as though my brain was a filing cabinet and every memory, good and bad had been topped onto the floor and mixed up and then stuffed back in with a good dose of WTAF? My life was upturned entirely. It didn't help that although I had proof and he eventually admitted it, nothing was done - the police said it wasn't a crime unless he intended to poison me, the doctors just seemed to rush me into "Oh well, just move on and build a new life" etc ..... I could go on. I posted about this here once and was told that weed wouldn't have caused that - well no, it was years of cumulative stress, manipulation and the complete breakdown of trust and boundaries plus the lack of serious care from the people I reached out to. So, I agree that trauma is a factor. For the record, I am now 9 years on, have rebuilt my life and am unmedicated, and despite huge amounts of stress have not had a recurrence. I am lucky. This all sounds like a paranoid conspiracy theory written down but it is true.
On the back of that, I am hardwired to see patterns and join dots, which is why conspiracy theories interest me. Often there is a grain of truth at the core of them. Some people may well think that all those Youtube videos are "proof" and become paranoid - if it affects their ability to function then yes, it becomes a mental health issue, and a crisis if they are prompted to do things that may harm themselves or others. (I was sectioned because I developed a bit of a Messianic delusion and tried to walk on water. I was rescued by some lovely windsurfers and thank heavens I was - my ex still will not accept that his actions could have caused me to die, and many people he has spoken to believe I was "over-reacting" when I had literally lost my reason - go figure....)
However, there's a vast distance between that sort of behaviour and just becoming a bore about things like 5G....... the former is a mental health crisis, the latter is something that will likely be replaced by the next "cause du jour"...... socially it can be a real pain, but in the particular uncertain times we're living in it does seem to reflect the uncertainty and lack of control we seem to be experiencing and people do like certainty and security - strip them of that and psychologically people will look for answers even when there really aren't any concrete ones.
Those who have mentioned the loss of faith are right to a degree although that too has its pitfalls - most people used to pray and put their faith in a higher power. That's now seen and irrational and unscientific. But sometimes reason fails us and accepting that we just have to "keep calm and carry on" is harder for some than others. When our leaders seem to be all over the place, confirmation bias will lead even very rational people to wonder if there isn't something more sinister afoot - and there might be. That's the rub. Who would have thought that the US government would give people syphilis and dose them unwittingly with LSD in the name of research in the 60s and 70s? This is documented fact from official sources. Have we moved on from that? are powerful humans also always morally sound and behaving ethically?
My Dad is a nuclear test veteran. He is part of the class action trying to get compensation from the government because he has splenic lymphoma, a very rare cancer. The MOD have spent many millions fighting this despite the fact that every other nuclear power automatically compensates its sick nuclear veterans, and all they want is an apology for using them as guinea pigs without their consent and maybe some cash to make their lives easier. But they won't allow sensitive documents to be released that might imply negligence or deliberate intent to experiment on the veterans. That is a real conspiracy in my eyes - and also the veterans have been painted as mentally unstable for trying to prove a link between their rare illnesses and disorders and nuclear testing...... draw your own conclusions but this is well-documented.
So, sorry for the mahoosive post - it's a fine line to tread, all this, but saying that if you accuse people questioning official narratives of mental illness, you're playing straight into the dictatorship handbook.
Free speech and thought are vital - transparency and accurate reporting are also vital.