EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.
Modified gravity theories are a well explored alternative to dark matter, but they aren’t popular for the simple reason that dark matter fits the observational data far, far better. Because currently there is evidence that something is there, extensive evidence.