Just a general piece of advice: when a person is discussing their struggles with psychotic delusions, its kind of messed up to say "Yeah, but how do you know they aren't real?"
Given the context in this conversation about how confirming a delusion can be dangerous, I think the concern is just that there may be situations where asking this genuine and interesting question could cause harm.
I think probably that on balance you've got away with it though because the people commenting seem to be safely outside the other side of their psychosis and are able to answer interestingly without being harmed by the question.
Yeah, it was odd because the first time I told a psychiatrist that I heard voices, it was because of a split-second incident out in the street where I swear I heard a distinct vocalization from the vicinity of a traffic light. No human was there, of course, and the illusion was over before it began.
That was enough to slap a prescription on me for years to come.
Eventually I began to question why they kept wanting to prescribe this stuff and why one of the standard questions was always "do you hear voices?" and I also began to question their terminology. "What do you mean, by hearing voices?" "Oh, well, hallucinations." and I drilled down into their definitions and epistemology for a while.
I told them that I am a Christian, and of course I hear voices. People of faith, who are quite sane, discuss this openly all the time. We are always encouraged to listen to the voice of Jesus, the voice of the Holy Spirit, to listen to the voices of those who wrote Sacred Scripture. I told the doc that I'd be crazy (and lost, and significantly more troubled) if I didn't hear anyone's voice.
Of course they're probing for stuff to medicate, they're probing for irrationality, and they're probing for evil voices who goad us to do harm to ourselves or to others. And of course I was troubled by those types too.
But they weren't unreal. They weren't hallucinations because the sources exist in reality. They don't come from human bodies, but spirits are real to Christians.
The solution is not to medicate the voices or deny that the voices exist or to ignore the voices, it's to form our consciences so that we can stand up to lies, stand up to temptation, and resist evil. It's as simple as that. Whether the voices come from Mom and Dad, or social media, or television, or they're 100% in our heads, we need to discern their spirits, and deal with them according to our conscience.
It was so jarring that the doctors would be goading me to deny my faith in this way and to claim that if I heard a voice encouraging me in a moral direction, that it was fake, a hallucination, a disease. I have been so profoundly insulted. This is one of the many reasons I lost trust in them.
Then again, I treat my whole life is a fascinating science experiment and people have to beg me to stop talking about it.