Oh, by "the rules everything else follows" you didn't mean the basics of quantum mechanics and energy conservation and such, you meant the exact current model o

Oh, by "the rules everything else follows" you didn't mean the basics of quantum mechanics and energy conservation and such, you meant the exact current model of physics that literally everyone with the slightest clue admits is wrong or incomplete. FWIW, the standard model already has plenty of particles that don't interact with EM, so you can't act like that's prima facie unreasonable. The story of the discovery of neutrinos is particularly relevant. Anyway, feel free to read around in this thread for the multiple other lines of evidence that lead to dark matter. Or read the Wikipedia article on it. The information is out there, if you want to know. Or you can keep making up strained analogies involving the number 85%. No one can stop you.