First of all, you are only ASSUMING that so called "Schizophrenic" people are actually experiencing hallucinations!
Put a primitive monkey in front of a mirror. Now place a chimpanzee in front of another mirror. The primitive monkey sees another monkey, and is fascinated at how this "other" monkey moves when he moves, and at how the "other" monkey disappears completely whenever he looks behind the mirror. The chimpanzee on the other hand, sees an image of himself and is fascinated at seeing his lips, teeth, mouth, facial hair, etc., and suddenly understands why the female chimps are always after him, now that he can see just how incredibly handsome a chimp he truly is.
If the primitive monkey could speak, he would be saying that obviously the chimp is experiencing hallucinations due to the chimp being in a delusional state of mind. The crazy chimp is claiming to be seeing some crazy thing called the "self" in the mirror, while at the same time it is bloody obvious to everyone else that the chimp is truly just looking at another chimp, and that is all.
Now picture chimps and how they view Human beings.
Since the human beings are more advanced than the chimpanzees, the humans can see things and understand things that the chimps can not. Therefore with this being the case, the chimps would be chatting about the fact that the humans were experiencing hallucinations due to the humans being in a delusional state of mind, which was why the humans were constantly talking about things that did not really exist, things that just weren't really there at all, and the proof of this was overwelming because ALL of the chimps certainly couldn't see what these crazy humans were claiming to be seeing.
Thus if 1% of the human population was a tad ahead of the rest, the rest of the population would classify these specific people as delusional people since they can see things that the rest of the population crearly can not.