I don't see that to be the case. Physicists have been giving their utmost to try to crack open the standard model and prove it wrong for decades. And the same is true elsewhere as well. We thought we had a pretty good grasp on the nature of the expansion of the Universe, but it turned out that the expansion is accelerating. That was a huge reformulation of cosmology. We thought we knew about planetary formation, but once we started finding exoplanets we discovered many of our assumptions were wrong.
As far as black holes, we have not 100% direct evidence of them, but we do have many independent and very strong lines of indirect evidence. For example, we can see stars in orbit around an incredibly massive object at the center of our galaxy (Sgr A*) that is not luminous. There are no models that make sense for anything that could be so massive and so dark. Black holes are the only theory which fits all the evidence we have, that's how science works.
As far as black holes, we have not 100% direct evidence of them, but we do have many independent and very strong lines of indirect evidence. For example, we can see stars in orbit around an incredibly massive object at the center of our galaxy (Sgr A*) that is not luminous. There are no models that make sense for anything that could be so massive and so dark. Black holes are the only theory which fits all the evidence we have, that's how science works.