I know what I am going to say is controversial but it proved true with me. I do not believe people are suffering from parasites or bacteria. I think it all oxidative stress.
That's an interesting belief, but many here have tested positive for reactivated viruses or chronic bacterial infections. In my case, I have Lyme and Bartonella, probably dating back 20 years to when I was living in rural Oklahoma and had hundreds of tick bites. Several symptoms started then, though most progressed somewhat through the years, until a viral illness and onset of constant and disabling ME/SEID symptoms. Treatment is still underway, but has been helpful thus far.
NAC should never be used. Ever. Nor malic acid or inositol. If you take these and you have SNPs that cannot handle them you will feel like poop. NAC and Inositol were two that were bad for me. The NAC made me make too many sulfites and the inositol made me feel like I was on speed.
Many studies contradict your advice. NAC has been studied long-term in HIV patients, and has had some beneficial effects with no appreciable side-effects, even at relatively high doses. Anecdotally, it resolves my "wired" cognitive issues, and accordingly has resolved my sleep issues.
It's important to recognize that your personal experiences cannot be universally applied, especially when contradicted by superior evidence.