Why not? Shouldn't a Universe comprised of 90% dark matter allow us to assume that our galaxy would be similarly endowed.Not directly inferred, no, but observations of the velocities of the stars and clouds of Hydrogen that orbit the galactic center indicate that the mass distribution of matter in the galaxy is not all accounted for by the clouds of gas and stars that are observed, hence inference of dark matter.
It was my understanding that dark matter "clumps". If that is indeed the case why don't astro guys observe light bending in our galaxy where it otherwise wouldnot be indicated?