Because it's fascinating. I don't really know what fibromyalgia is, but people faking pain/illness for attention is absolutely a real phenomenon that 100% occurs.
I used to work with a woman who absolutely faked illnesses in her children. The number and frequency of her kids' ailments was staggering, and shockingly topical. If there was a new illness going around, they always got it first. If someone brought up an allergy, they had it too. Her kids had multiple seizures, anaphylaxis, Lyme disease, SARS, pneumonia, etc, all in the course of 12 months, with multiple occurrences of several of them. She missed almost 25% of work days for an entire calendar year, due to sickness in her kids.
There was no fathomable way that her kids were that sick all of the time.
And that's fascinating that some people will do that, and will continue to do it, even after all believability has been exhausted.
I'm not passing judgement, but it's definitely something that is interesting as hell, and worthy of study.