system
A chat on subreddit /r/me_irl
human
There are *some* people who don't have an inner monolog but it's absolutely not 50-70% of people.
gpt
Yeah other studies have put this closer to 70 percent with an inner monolouge and 30 percent without. 

But for sure those without are NPCs (jk)

No inner-voice seems to correlate with high extroversion, and also with low levels of education.