Your anxiety might come from a feeling of uncertainty of what is to come and helplessness in face of that. In my opinion self-efficacy works wonders for mental health, so maybe pick a job or other activity actually trying to work against the world going down the drain (or at least giving you the feeling that you do) instead of accepting that it is "invariably" happening.
It certainly does come from a place of uncertainty. I'm trying to work in the space industry in an effort to feel like I'm positively affecting humanity, but I'm not currently having a lot of luck.
No, the other advice is actually more helpful. Rather, this is the first who validated your anxiety.