I'm at about 65/35 that most of what we think of as "long covid" is really just psychosomatic. If you define "long covid" very broadly to include people who have a symptom or two that lingers for a while, that obviously exists in the real world. But it is pretty unlikely to be the case that a significant number of people suffer serious harm. We would be seeing them all over the place by now, and we just don't. I'm also heavily influenced here by the fact that a large number of people are just irrationally afraid of covid -- that type of person is going to be prone to making a mountain out of their infection molehill.
I don't think it's psychosomatic, but I also think that, at least so far,
Long Covid is so vaguely defined that it's hard to conduct any meaningful studies on it. The symptoms vary so widely across different people AND there is no isolated physiological cause. If it were only one of those, maybe there'd be something to work with. I mean, a Covid infection itself has varying symptoms depending on the person, but you at least know that they all were caused by the same thing: the SARS-CoV2 virus colonizing their respiratory system. Similarly, if there were a percentage of Covid cases where people were all continuing to suffer, say, unusual levels of fatigue for months afterward, you could look for patterns among that population.
But if you're trying to study one person who has fatigue for a couple months and another who has brain fog for a year and a half, and you don't know physiologically what separates either of them from the person who had mild flu-like symptoms for 24 hours, what the hell are you supposed to analyze?
Maybe at some point we'll come up with a more precise definition, or maybe we'll discover the physiological differentiator in Long Covid cases, but until that point I'm setting my expectations low that we'll have any significant insights