But if you do the math, that means for every star-orbiting planet like ours in the galaxy, there may be up to 100,000 planets that not only don’t orbit one now, but most likely never did.
The sun is around 330,000 times more massive than the Earth. Thus those 100,000 other Earths out there have a mass of 1/3 our sun. But, there are of course several other planets in our solar system. So the mass of all those rogue planets (100,000 : 1 ratio of rogue planets to planets in the solar system) would be several times greater than the sun. Not exactly a trivial amount of mass there. That could explain a big part of dark matter, but of course people a lot smarter than me have already considered and dismissed that already for whatever reason. Maybe they've already accounted for that much extra mass and there's still the "dark matter" that's missing.