Using Peterson's estimate: Nineteen million patients world wide. Every year they experience a years worth of torment and suffering. So that is nineteen million person years of suffering, every year, for people with a disease that is being ignored. Even in the US alone that is a million years of suffering per year, presuming the one million estimate. If its really four million ....
In one sense, it matters which estimate, but in another way, it doesn't matter. All people with ICF are treated the same as us: "you don't belong in the doctor's office, go see a shrink or handle it yourself". Regardless of whether they have ME, MS, cancer, hypoparathyroidism, or whatever: they are not getting any help. No "fatigue" patient is.
(Edit: this is a generalization, representing a common scenario. Of course some patients get diagnosed eventually, but there is a staggeringly huge number of undiagnosed and misdiagnosed patients who present with fatigue and/or describe weakness which gets brushed off as 'just another case of common fatigue')
Until someone gets their feet off the desk and goes to work telling doctors why and how to diagnose patients more carefully, and finding the funding to do research for ME properly, this situation will continue.
People will suffer. Every minute of every day. Some will die.
And as has been said, great talent will be lost to the world (not that all of us are talented, but out of so many, surely some are talented scientists, mathematicians, engineers, economists, etc.). We are shut up in our houses or rooms, without proper care, unable to finish school, go to work, or even have normal social lives (just a little, mostly through our computers, except the most ill of us).