Especially with LLMs getting better at hacking, do not treat this forum as entirely secure. Do not send DMs with passwords or crypto wallets. Do not organize affairs in DMs. This forum is not an appropriate place for high value private data.
This forum uses the Discourse open source software. They don’t have a huge budget. I imagine the security is decent.
If you want to communicate securely with someone online, my general recommendation is https://signal.org
Inspired by: https://www.lesswrong.com/posts/2wi5mCLSkZo2ky32p/do-not-be-surprised-if-lesswrong-gets-hacked