Stuff I have seen:
- LSD usage is pretty common relative to where I grew up (midwest-ish), but usually rare (once a year, burning man, someone has tried it once) even so, I'd still guess this is a pretty small minority - I guess 15% max? I'd guess mostly this is curiosity driven, reading about it, etc. I've never seen anyone seriously use it as a productivity drug.
- Adderall is more common, but that's because it's prescribed (and it works well so everyone thinks they have ADHD if they take it) - I haven't seen it abused, I've heard people talk about modafinil but have never met anyone that was actually taking it. Even in the adderall/adhd case, I'd guess 20% max? Most people I work with do not take it.
- Ketamine I don't know anyone that's tried it beyond someone in the therapy trials and non-techie druggie types.
Maybe it's more common and I'm not in the right circles, but I don't really buy it. I think it's rare and elevated by articles like this because it's salacious not because it's common. I'd guess my made up percentages are also too high.
There's strong selection bias with drug use because drug users tend to cluster together, I suspect it's a lot less common than people think.
Demand is not what the weed industry thought it would be.[1]
[1] https://www.foodengineeringmag.com/articles/99944-price-per-...
Wouldn't be surprised if he is also microdosing LSD, it is quite popular right now in high-tech circles (see: https://www.wsj.com/articles/silicon-valley-microdosing-keta... ), but I don't think someone has accused him of that yet.