Something is comprising the universe that we haven't found yet. Perhaps this substance isn't 'dark' or even 'matter', but 'dark matter' is a reference to the 70% of the composition of the universe that we have yet to truly discover.

'Dark matter' isn't a reference to something that has been described, it's a reference to something that hasn't been yet described. Only once we can describe it can we argue it's existence, because at the moment, there is no question that it exists...

There is no question because SOMETHING has to comprise the 70% of the universe that we haven't described yet! Whatever that undiscovered something is, we call it 'dark matter' right now.

It will be a fine day for the scientific community once we really discover the properties of 'dark matter'. It will be a fine day for the comedic community if the properties of 'dark matter', ironically, are not dark or consist of matter.

Yes dark matter exists. Our universe is flat like a sheet of paper, as you know there is this thing called space time and it's believed to be a fabric that is warped by missive objects like stars and planets and all that good stuff. Dark matter could be one of a few things. I personally believe that dark matter is just matter from another parallel universe that we cannot see. In physics you learn that everything is gravitationally attracted to everything and it is calculated quite easily G= (m1) (m2)/r2. Black holes are super massive expanses of inescapable gravity which would be a link to these other universes. Think about it? Where does the matter which is sucked into a black hole go? It could be going to this other universe which is parallel to our own but invisible because it has no interaction with light or the electromagnetic force. This other universe could be inches away and we wouldn't be able to see it because light travels between the two universes. However gravity goes between universes because it is the bending of space. dark matter in truth is four times more common than "regular" matter if you add up all the force of the matter in our universe that is visible then it is not enough to hold the planets galaxies and everything we know together this there has to be more invisible matter holding everything together acting as an invisible rope. So basically yes dark matter is real we just can't see it but it can be calculated by finding the velocity of stars and planets that are far away from the center of the galaxy compared to the velocity of those that are closer to the center. (One would guess that the stars close to the center are faster and the ones farther away are slower just like the planets in our solar systems however this is not the truth they are equal)