Fascinating idea.
I've noticed it for a couple of years or more now. I figured most readers of HN have also noticed it, so I thought I would throw it out there to see if my observation was shared or not.
I know that people cycle through moods in their lives. I also know that people require some amount of drama in order to feel as if they have meaning (Even/especially people who say they don't like drama). Doomscrolling and the associated content promotion, curation, and aggregation probably tap into that primal need.
The internet at scale and the associated Markov-chain-like content selection and promotion we're seeing is hacking the species in some very significant and unexplored ways. Between the folks completely in denial and those claiming that the end is near, there needs to be some real philosophy and science going on (I don't think either one by itself is going to help much since this is a completely new area of intellectual exploration)
*(Reference to phrase "Sunday Scaries" for those who haven't seen it before: www.sunday-scaries.com/what-are-sunday-scaries )