I think you're missing an important aspect. Moses and many other biblical prophets were very high functioning. They were not only able to complete basic life tasks, but in many cases were compelling and magnetic people who engendered trust and reverence from others.
That makes diagnoses like severe schizophrenia (enough to cause visual and aural hallucinations) very unlikely. Somebody who thought bushes were speaking to him could not have fed himself, let alone led anybody anywhere.
The most likely diagnosis of all of your famous prophets is probably narcissistic personality disorder, or the experimental diagnosis of malignant narcissism.
This diagnosis would mean that Moses didn't actually see or hear any of that stuff. He just had such a need for recognition that he told people he did. His brain may have created delusions to satisfy his ego. He may or may not have believed himself.
Charles Manson, for example, believes himself. L. Ron Hubbard did not.
I'm not sure if that means much or is that clear.
For a start, Jim Jones also was a very effective and convincing cult leader, but not only he got himself and his whole cult to poison their babies and kill themselves, but it turns out they had been drilling exactly that for a long time. Which isn't exactly the sanest thing to do. Spending years practicing your eventual suicide, as well as the death of everyone who ever trusted you, every day, is the kind of thing that would get you sent to a competent psychiatrist.
Plus, not all schizophrenics are drooling wrecks. Simple schizophrenia, sure, eventually it is, but even that one after a long time. It's a downward path in being more and more broken, than just suddenly being unable to care for oneself. Paranoid schizophrenia on the other hand can leave one an otherwise intelligent and functioning human, but still seeing ghosts or having surrealistic delusions or whatnot on a regular basis.
Second, we're talking relatively rich and powerful people, and past a point even just having a gaggle of trusted people to delegate to would take care of most things. It doesn't matter if you're too crazy to tie your own shoelaces, if you've got people who consider it an honour to tie them for you.
E.g., does it really matter if Moses was sane enough to be able to survive on his own alone, when basically at every step he has his brother doing even the getting his message to the people? And I mean, really, Moses doesn't even have to be coherent enough to convince his followers or the Pharaoh, when he has Aron as a very skilled spokesman taking care of exactly that for him.
And in fact one even has to wonder if such an Aron character wouldn't be the originator of such stuff, if he has a crazy guy that's believed to be a prophet and that he can manipulate or just in whose mouth he can put whatever he wants. How much of the wise stuff would have to be even directly from Moses, and how much can just be at least edited by Aron into something wise(r) sounding than Moses's ramblings.
Third, taking care of oneself is something that some of those figures fail. Being "crazy" doesn't necessarily mean failing every single thing. And if someone's delusions actually get one killed, I'd say that's pretty much the ultimate proof that, yes, they were too crazy to care for themselves.
E.g., that woman who put her arse in a propeller because God told her to, it doesn't matter how rational or able to care for herself was the rest of the time. That's the failure that proves right there and then that she wasn't sane after all.
Now let's look at the example of another mythical character: Jesus. (Mind you, I still don't believe he's historical, but we're playing by hypothetical premises, right?) He talks to God to the extent he's convinced that God told him to go get himself killed by the Romans, and he does just that. Plus some surrealistically delusional episodes along the way, such as his having a major fit at the... currency exchange guys at the temple, who were just there for people coming from other cities (a lot even around Passover) and who needed the exact coinage for the entrance fee. But anyway, I'd say that getting himself not just killed, but killed in the longest, most painful and most dishonourable for his family execution available at the time, is exactly proof that he wasn't able to care for himself enough to keep himself alive.
