I've been on SL for probably longer than is healthy, lol.
I don't think Second Life is inherently toxic. I do think there are toxic spaces within it, though. My best advice for those is if they don't pass the vibe check, find a new hangout. Leaving sucks but your mental well-being is always the most important thing.
I think the most pressing thing is fear of change, though. It's something that I've seen come and go in cycles with any big change or new feature. Ultimately, the fears never come to bear each new big feature. Sometimes perhaps a disappointment of LL not going far enough but never catastrophe. I remember when people lost their minds over mesh and declared no-mesh zones. Those no-mesh zones are gone. It turns out that people moved on and adapted. Those that didn't, left. And that's okay. It didn't doom Second Life.
As with Windlight, as with mesh, as with advanced lighting model, as with EEP: We will get through this with glTF/PBR and Second Life will survive and be a little better for a little while.