We have gravitational evidence. We can only ever infer the existence of anything. An example of this is we didn’t actually see the Higgs Boson we just deduced it’s existence from the cascade of interactions that happens when particles collide. Similarly we can deduce from the gravitational evidence that dark matter exists.
We don’t because we have experimental evidence for it’s existence.
No we don’t
We have gravitational evidence. We can only ever infer the existence of anything. An example of this is we didn’t actually see the Higgs Boson we just deduced it’s existence from the cascade of interactions that happens when particles collide. Similarly we can deduce from the gravitational evidence that dark matter exists.