I'd put the figure a lot higher than that, although it depends if you're talking about people who post on bluelight, or the general population.
Maybe roughly 10 % or so of bluelight contributors used and / or enjoyed the pvps, but when you get into the obscure dissos like 4 meo-pcp it's more like 1 in 1,000 or 1 in 10,000 bluelight members it seems to me.
If you're talking general population it maybe numbers far greater like 1 in 100,000.
Its easy to forget how much bluelight distorts ones perception of how common drug use is, as obviously nearly everyone that posts on here uses, or has used drugs, and mostly in a very big way.
Use of those rare drugs in the general population would be like less than 1 in 1000 or 10,000, no idea really, just very very rare.
Ask your average GP or drugs worker if they've even heard of those things, not a chance....