A black hole is made up of an infinitely dense point-mass singularity and an event horizon. Nobody has every found either. So nobody has found a black hole.
This is astronomy, we have only photons or the lack thereof and our interpretations of these photons and their lack. We haven't even sent a probe yet to the surface of the Sun (we have gotten eleven million miles away). So, by "direct observation" standards, we don't even know the Sun exists.
For your standard, we would need to send ships to each star, including the event horizon of a black hole. These aren't standards we can do anything with.
For your standard, we would need to send ships to each star, including the event horizon of a black hole. These aren't standards we can do anything with.