There was a support group in an area I used to live in. It vaguely included NTHE in the name. And frankly I might have been better off if I had never participated. I did get to talk about my feelings on climate change, so that was nice. But the drama and infighting was unreal for a group with the ostensible purpose of discussing the likely upcoming extinction of our species. I suspect the topic was so far outside the Overton window it just attracted people accustomed to being on the fringe. Even the one or two we made friends with were too unstable to maintain a friendship.

So I recommend against describing your social group in terms of doomers, or extinction, or anything that will seem like too much for most people to accept. If I wanted to start a social gathering of some sort I would maybe make the focus on climate change or prepping or something that more people can consider realistic. Then just try and get to know the people who show up. Odds are some of them will have similar views and be looking for people they can talk with.

Of course I have also introduced the concept to a few open minded people who took it seriously and have embraced it (so far). That's another approach. It's pretty obvious something is different now and things are getting worse. There are some people who don't know why and would like to. It's a crap shoot though. Many (especially parents) just can't deal with it. But some can. So if you can have a real conversation with someone you know, give it a try. Talk about James Hansen's projections, or how we can't fix the climate damage we've done, or whatever your thing is and see how they take it.