I think the 1% figure is inflated because the definition of "stutter" is so vague. Those of us in this reddit are talking about pathological stuttering, i.e. COFD. Someone with this condition, when they encounter a block, cannot just will themselves through it. They encounter a hard wall of sorts, the nature of which isn't well understood. And then there's regular stuttering, of the kind regular people do. This is the more general definition of stuttering which nearly every speaking individual has done at least once in their lifetime. The fact that the two are so often conflated is why so much bad advice exists about COFD online, because it comes from neurotypical folks who experience temporary, mild disfluencies that are capable of "willing" themselves through it by just trying again. This conflation is also why I believe the 1 in 100 figure is inflated too. If you account for the gender ratio among stutterers, that means 1 in 50 adult males has this condition, which is a staggering amount. And yet most of us with COFD don't encounter other stutterers with this frequency. You would especially expect to see this in male majority spaces or professions, for example among engineers, cops, or the military, and yet people with these backgrounds rarely report knowing colleagues with this condition.