Here are some comments that were down-voted by the Hacker News community regarding "Dark Matter" ...

Title: The Reason We Haven’t Directly Detected Dark Matter (medium.com)
https://news.ycombinator.com/item?id=18207276
>[mixmastamyk 1 hour ago] Believe the issue people have with “dark matter” is really about the term, it points to a so-far unprovable solution as a goal rather than a problem. It elevates a hypothesis to already solved, just need evidence. If they called it the “galactic paradox” it would be more easily recognized as a problem to work on. You can downvote but it only proves the perception problem, not wanting to hear it doesn’t help.
>[lottin 5 hours ago] So, basically physicists have deduced two facts, and these facts don't agree with one another. From this they conclude that there must be something else in the universe, something unseen and undetectable, that they call dark matter. But what about the other possibility, which seems far more reasonable to me, that either one of the facts is wrong?
>[std_throwawayay 5 hours ago] If we can't detect it or disprove it, it doesn't even belong to science. It belongs to the same realm as witches and demons - until some smart physicist devises a way to actually detect it.
>[roenxi 5 hours ago] Our understanding of gravity might be completely wrong. If 85% of the gravity is unexplainable that seems like a pretty safe bet. Maybe it just behaves very differently at galactic scale. Much like the aether, it seemed most likely that light traveled through a medium until it turned out that it probably doesn't.
>[skdjii 5 hours ago] Another reason may be that dark matter doesn't exist. If the universe consists of 85% of the stuff it would seem that it should be easy to find. Occams razor should apply as usual.
>[user812 6 hours ago]Indeed. Physics is wrong on many fundamental levels, but everytime physicists find fundamental errors, they propose another entirely theoretical layer of complexity, with the "benfit" that no one is able to practically refute it.
>[tychomaz 6 hours ago] Because it doesn’t exist. Dark matter is a fudge factor to prop-up a theory that astrophysics is too afraid to put to rest.