Updated: Oct 15, 2021
Dark Matter is of course the other famous kluge of the Big Bang model. In fact, the only successful Big Bang model right now is the lambda cold Dark Matter model which relies thoroughly on both Dark Energy and Dark Matter in order to make the model work.
But that's the problem with kluges. Dark Matter, which has never been directly observed, has been defined precisely by the gaps in the existing theory. So the explanation only works because it has been carefully designed to paper over the flaws in the model. That's what a kluge is.
And since we have never observed a Dark Matter particle, despite over two decades of intense observation and many Large Hadron collisions, we cannot, in any direct way, test whether the kluge is defining a real thing.
Even besides the inelegance of Dark Matter, there are some real problems with its use in the Big Bang model. In the lambda cold Dark Matter model, Dark Matter is assumed to have gravitationally clumped together first, before regular matter, and then gravitationally drawn matter to it, forming the filament structures of the cosmic web. However, if Dark Matter is clumpy like that, then we should probably see evidence of at least some clumpiness within our own galaxy. But we don’t. If we ignore objects outside of our galaxy for a second and just look at the movement of objects within our solar system and our galaxy, we see zero evidence of Dark Matter.
Dark Matter theory says that our galaxy should have at least five times more Dark Matter than regular matter, in terms of gravitational effects. But when we look at planets and stars in our galaxy, we see no such effect. Everything works according to General Relativity, as if the visible mass was all that was there. If Dark Matter was present, and was gravitationally clumpy, then it probably should clump where regular matter already is. There should be a dense ball of Dark Matter around Galactic center, for example, because that’s where the greatest gravity well in our galaxy is. We should see less dense spheres of Dark Matter at our sun and at earth and Jupiter. But we do not. The movement of the earth, the sun, and all the stars around Galactic center, conform to the rules of General Relativity, precisely, without any apparent effect by invisible matter.
The proponents of the lambda cold Dark Matter model get around this problem by saying that Dark Matter is clumpy, but it's not that clumpy. So it was clumpy enough to act in opposition of expansion, to collapse upon itself, to form the cosmic web and draw all matter to it, and to bend spacetime like a lens, and it’s gravitationally powerful enough to spin a galaxy five times faster than we expect, but somehow it's not clumpy enough to, in any way, affect the relative movement of objects within the solar system or within the galaxy.
Plus, Dark Matter doesn’t seem to interact with itself by any other known force than gravity. When regular matter collapses in on itself, it is the electromagnetic, weak and strong nuclear forces that keep it from collapsing all the way to a black hole. But since Dark Matter doesn’t seem to be affected by any of those forces, its clumpiness should have all collapsed into black holes, long ago. Or should have never expanded with spacetime, back at the beginning. As we established earlier, expansion has always been stronger than gravity. So, if Dark Matter is so clumpy that it can defy expansion, then it probably should have never expanded at all.
Plus, of course, science already has a beautifully elegant and successful model for predicting new particles: the Standard Model of Quantum Physics. There is currently no room in the Standard Model for Dark Matter. WIMPs have already been mostly ruled out, and neutrinos are such poor candidates, that they had to hypothesize a new kind, the Sterile Neutrino, which is just another kluge. It’s possible that we may yet stumble across a new physics in searching for Dark Matter, but a more elegant solution would also agree with our most successful predictive theories, without having to invent exotic new energies and matter.
Dark Matter is a kluge upon a kluge upon a kluge.
Edit: my own research on Dark Matter is relatively uninformed, so I refer you to a series of data-driven exceptions, as gathered by Astrophysicist Pavel Kroupa: https://www.youtube.com/watch?v=PVgwLWVETIM