In almost every talk related to dark matter there is a slide about the evidence for dark matter. One of the quoted evidence is always the Bullet Cluster. This argument for dark matter was introduced in
This argument for dark matter is repeated over and over again: in lectures, talks, seminar etc.
No one challenges this claim, although it is not really a strong argument for dark matter. This is dicussed nicely, in
Her point is that its extremely unlikely that an event like the Bullet Cluster collision happens if dark matter exists. So she concludes:
The Bullet Cluster isn’t the incontrovertible evidence for particle dark matter that you have been told it is. It’s possible to explain the Bullet Cluster with models of modified gravity. And it’s difficult to explain it with particle dark matter.The Bullet Cluster as Evidence against Dark Matter by Hossenfelder
While you can certainly disagree with her, the point is that you never hear about both sides. Students are always only taught about the standard story and never hear about alternatives.