Why is space so dark even though the universe is filled with stars?

We still don't know what dark matter is, but here's what it's not

Olbers's paradox - Wikipedia

Black holes may have existed since the beginning of time (and could explain dark matter mystery)

Dark stars: Have we finally found a weird sun powered by dark matter?

14: Astronomers Watch Black Hole Devour Star

Martian meteorite questions traditional model of planet formation - SpaceChatter

Mystery solved: how to make galaxies without dark matter - Big Think

This Planet Is So Dark Scientists Have to Guess What It Looks Like

Physics: Why is the universe dark? - Quora