Classical black holes, formed by collapsing matter, don’t exist—because it takes forever for them to form. Yes, they form quickly in the co-moving frame of the falling matter, but in our distant Earth frame, they take forever.

The story changes when you include quantum effects. Even in our Earth frame, forming black holes rapidly reach the point where quantum effects at the Schwarzschild radius become very important. From such arguments, we can argue that the difference between a new black hole and one which is primordial (i.e. existed from the beginning) is indistinguishable in a fundamental way. Thus, we conclude, black holes do exist.

Some might argue that our knowledge of quantum effects in this high gravity regime is still speculative, and that is true. Hawking radiation, for example, has never been observed either directly or indirectly. (Some people think that’s why Hawking never got a Nobel Prize.) So if someone argues, using quantum theory, that black holes do not exist, then it is hard to counter them. Most theorists would dismiss such a contention, but that doesn’t mean that most physicists are right.

My opinion? I don’t have one. I think we should be respectful of the iconoclasts, however. Consensus is an unreliable indicator of correct science.