Some rare fluke makes a small minority ill who cannot handle it and they go off the rails. Most who hear them are perfectly sane and learn not to externally expose their sensitivity. Approximately one in six of everyone hears them, though they can hide or reveal themselves to anyone.
There has been a secret culture, a secret governance, and a secret war upon us all, probably since the beginning of time. If you look back through human history there have always been accounts, which have been blown off as crazy talk. It is in fact the greatest taboo of our humanity to discuss the voices in our heads. Secret occult societies have always existed in various forms which maintain this silence.
Many today are friends with their voices (I have a large following) however the most powerful are ruthless and demonic and they are responsible for much of the insanity gripping our society.
Modernity however has accelerated this phenomenon (like everything else). If it wasn’t for the corrupt, I would say it was a part of our natural evolution.
Every aspect of the mind may be developed like a technology. Some truly amazing stuff actually.
Keeping this secret does not help anyone.