There is little ideological overlap between rationalists and Rust folks (and thank god for that). IME unlike the rationalists, Rust has actually done something useful for the world, and HN’s opinion of Rust and its community has drastically improved over the last decade.
The rationalists have not had any such clearly positive effects, and rather their adherents (Thiel, Vance, etc) have had severely deleterious effects on society.
There is no comparison between the two communities.
I don't know much about Thiel, but Vance does not seem like an "adherent" of rationalism in any way I recognize. I have trouble imagining Vance talking about "The Sequences" or "AI x-risk."
Mentioning Thiel and Vance together brings to mind a different thread of weird netizen philosophizing - one I don't really know much about but which I guess I'd sum up as the "Moldbug / Curtis Yarvin fandom." "Neoreactionaries" might be the right term?
I definitely recognize that the Venn diagram between those two "intellectual movements" (big scare quotes there) overlaps quite a bit, but it seems like a bit of stretch to lump what Vance, Thiel, and other right-wing tech bro types are up to under the rationalism banner.
Update: Having read through some of the other links in the thread, I have "updated" (as the rationalists say) my mental model of that Venn diagram to be slightly more overlapping. I still think they're distinct, but there's more cross-pollination between the Moldbugs and the ACX crowd than I initially realized.
The rationalists have not had any such clearly positive effects, and rather their adherents (Thiel, Vance, etc) have had severely deleterious effects on society.
There is no comparison between the two communities.