These are the people who came up with Roko's Basilisk, Effective Altruism and spawned the Zizians. I think Robert Evans described them not as a cult but as a cult incubator, or something along those lines.

YCombinator but for cults

Effective altruism wasn't started by the Berkeley rationalists.

They have separate origins, but have come to overlap.

so many of the people i’ve read in these rationalist groups sound like they need a hug and therapy

They seem to have a lot in common with the People's Front of Judea (or the Judian People's Front, for that matter).

Also:

* Communal living

* Sacred texts & knowledge

* Doomsday predictions

* Guru/prophet lives on the largesse of followers

It's rich for a group that claims to reason based on priors to completely ignore that they possess all the major defining characteristics of a cult.

Below is a list of cult markers I posted here the last time this came up. It recaps some of the bullet points above.

1. Apocalyptic world view.

2. Charismatic and/or exploitative leader.

3. Insularity.

4. Esoteric jargon.

5. Lack of transparency or accountability (often about finances or governance).

6. Communal living arrangements.

7. Sexual mores outside social norms, especially around the leader.

8. Schismatic offshoots.

9. Outsized appeal and/or outreach to the socially vulnerable.

Also, mandatory scriptures and group hiouses.