while innumerable other people who obsessively watch their diet, spend most of their day in a warm bed, and take a couple dozen supplements every day are sick.
You might have cause and effect reversed. Pre ME/CFS, I didn't need megadoses of vitamins and supplements to function. I had a fairly nutritious diet, never did eat a lot of sugar or white flour etc. and was able to work full-time plus be physically active after work and on the week-ends - long walks, bike rides etc.
Post-onset of ME/CFS, I could no longer do any of those things. And in a desperate quest to improve my functioning, found the hard way that forcing myself to try to push through exhaustion didn't work and only made me sicker. I was forced to spend much of my day "in a warm bed" as you put it. I didn't get sick because I was physically inactive, I was physically inactive because I was sick.
I found through a ton of reading and experimentation and seeing what worked for others that megadoses of certain things improved my energy and functioning. I didn't need these megadoses pre-ME/CFS. So these megadoses did not cause me to be sick; rather, they are the result of being sick. And they have helped. People who have known me for years are well aware that my functioning today is quite a bit better than 10 years ago, though still much more limited than a healthy person. And I have seen a direct correlation between certain supplements and improvement. There have also been dozens of other things I have tried that did not help me, and I no longer take those things.
innumerable people who get their dinner from a dumpster, supplement it with cheap wine, and sleep under a bridge are well...
Theoretically you could eat well out of a dumpster and if you're healthy to begin with, you'd probably do pretty well. It all depends on what you eat. If you eat a lot of sugary white flour food out of a dumpster, you'd be much more likely to develop the same conditions as your more wealthy brethren - diabetes, obesity, heart issues etc. But I agree, it is possible to get enough nutrition from a dumpster if you have a good dumpster.
About the wine, it depends on how much you drink of course. Anyone who drinks too much (whether cheap wine or expensive brandy) will damage their liver and can develop malnutrition etc. So cheap wine all by itself isn't harmful, it's just how much you drink.
And I believe that once an effective treatment for ME/CFS is found, I no longer will need these megadoses of supplements to function. But there seems to be something in the metabolic malfunctioning of ME/CFS that greatly increases the need for certain nutrients. Maybe it would be like trying to drive a car with flat tires. It would be hard to get going I would think so one would need a very powerful engine to push past the defect of the flat tires, if that makes any sense. And so megadoses of certain vitamins and supplements help me drive a bit better despite the flat tires.
And of course we are all so different, what I take might harm someone else or at the least not help them. We've all seen this. But we have all also seen so many people here who have been helped by sometimes megadoses (but not always mega doses) of various things. It's not all in our heads, this improvement in functioning.