A question for schizophenics, by a non-schizophrenic

Hi, I apologize if my question is stupid or offensive, I've never suffered from schizophrenia or psychosis, but I have a friend who does and I want to understand him better.

My question is: why do you feel compelled to do what the "voices" order you to do? My friend hears voices telling him to do something and he will always do it. I get that hearing voices must be incredibly distressing, but why do you feel the need to follow them blindly? Why do you put so much authority in them?