This is a misinterpretation of these studies which is common throughout this thread.
The research isn’t showing that chronic pain is a psychological condition. It’s suggesting that some cases of nonspecific chronic pain that specifically do not match the symptoms of typical physically-rooted pain are psychological. The participants in this study were filtered for this criteria.
For some reason, people see this idea and lose the nuance, concluding that most or all chronic pain is actually psychological.
I think if someone matches the description used by the author of the substack for this HN entry (he describes his chronic pain as random and popping up all over his body) then pursuing the psychological explanation would be a very good idea.
However, it’s getting frustrating to see all of the reductionist claims that “chronic pain is psychological”.