Did you know that the concept of “Dark Matter” was actually invented by primarily American novelists?
Belief in Dark Matter has roughly the same validity as a small child’s belief that there is a monster in his closet. He can’t see anything, his parents aren’t home, the closet is dark, and its properties don’t fit with his explanatory theory which has been accepted by his epistemic peers in the scientific community. Therefore there must be this ridiculous substance to explain his yucky feelings.
Physics is in a situation in which something like 90% of the matter in the Universe is what is called dark matter — it’s called dark because they don’t know what it is, they can’t find it, but it has to be there or the physical laws don’t work. So people happily go on with the assumption that we’re somehow missing 90% of the matter in the Universe.
There you have it, from an official and mainstream scholar of the natural sciences. What more do you need?
[EDIT: See part two in this series, here.]