I think it’s low level mental illness or some yet to be diagnosed mental condition. I don’t think it manifests itself strictly in Sov Cit folks. Think of those people who go full Don Quixote over some perceived wrong wrought onto them. They dig themselves in to fight something ridiculous and impossible to win -for they have no case- and spend their lives dedicated to it, never giving up or letting it go. The Sov Cit dudes at least have each other to commiserate.