I suspect that the author is off by a few orders of magnitude on scale: they say tens of thousands of people, but that would be one-in-ten-thousand adults. None

I suspect that the author is off by a few orders of magnitude on scale: they say tens of thousands of people, but that would be one-in-ten-thousand adults. None of us would've heard of it. I would guess tens of millions have tried BDSM in some form (1-in-10), and millions engage in it regularly (1-in-100) in the US.