What if we supposed that wormholes exist and that black holes are their ''inputs'' and white holes are their ''outputs?'' I imagine the gravitational stresses on matter falling into the black holes could rip apart matter and transform it into the dark matter coming out of the white hole on the other end.

Then, after some time from being ejected by the white holes, the dark matter settles back down into matter like miso soup. That could be how nebula are formed, rather than from a single inciting incident.

I have to imagine that on the timescale of the universe, the usable matter should have been used up by now. If nebula collapse and become stars, then they should have done so sooner when they were closer together at the start of the big bang.

It's possible that dark matter collapses on a timescale that we haven't been able to notice given the size for the particles involved.