So, um...indirect experimental evidence is not actually empirical. It is absolutely, completely un-the-same as experimental evidence.,
Um, no you don't understand. There is direct evidence that we can measure the total amount of mass and energy in the universe. However, 95% is unaccounted for if we count all the stars and planets scientists think exist. Therefore indirectly, dark matter is the placeholder for the matter that should exist but can't detect. They could have called it Zoidberg matter and it would be the same.
It's like looking at the ocean. With the naked eye we can only see the top layers of the ocean. Historically, sonar allows us to determine the depths of the ocean to be miles deep; however, until the existence of deep underwater vehicles, scientists didn't know what the bottom was like. They could only guess. They could not imagine that life exists near the Marianas Trench for example.
The case for dark matter is more inductive or abductive reasoning. Given certain premises based on our current understanding of gravity and our observations of the universe, dark matter makes sense. However, our observations could be wrong, or our models could be incorrect.
Yes everything in science could be wrong; however, you must prove that every one of their observations is incorrect rather than assume that because someone doesn't have all the answers, they don't have any answers.