Dark Matter: Over and Over, Scientists Have Made Wild Claims Prior To Having Any Actual Evidence.

 Dark matter, according to mathematical models, makes up three-quarters of all the matter in the universe. But it's never been seen or fully explained. ... Now, an international team of scientists says it has found new evidence that perhaps dark matter doesn't really exist after all.6 Jan 2021

https://www.nbcnews.com/science/space/maybe-dark-matter-doesn-t-exist-after-all-new-research-n1252995