For many of them it could be that they expect to feel better than they do, buy how they feel is closer to normal than they realize, given their body fat %, blood pressure, cholesterol, triglycerides, atherosclerosis, breathing problems, prediabetes, acid reflux, etc. They are feeling bad compared to their parents and grandparents at their age, but not due to what people normally think of as a medical condition.
CFS is much more debilitating than you make it sound and it is not about "feeling bad". Some patients are effectively bedridden.
The disease is very poorly understood but one common symptom seems to be a low tolerance for excercise. CFS patients recover very poorly from exercise, and a day of even moderately increased physical ativity may cause them to "crash" and become debilitated for multiple days.
It is also worth mentioning that CFS patients often have normal results for cholesterol, blood pressure and so on. One reason why biomarker studies like this one are important is exactly because currently CFS patients often end up bouncing from doctor to doctor, and none of the diagnosis ever work.
I don't know whether you've experienced chronic fatigue, but from your comments on this thread it looks like you haven't. It is dramatically more debilitating than you seem to give it credit for. (I haven't personally suffered from CFS, but I know people who have. Additionally, I have experienced months of insomnia which resulted in my being unable to do pretty much anything - lack of sleep is truly crippling - and I can only presume that CFS makes you feel much worse in a wide variety of ways.)
You clearly have a very wrong idea about cfs. Walking 100 meters and then you’re very sick for a couple of days, that’s cfs. Can’t get out of bed sick.
