Haha!Do you understand how black holes work? Obviously not, no one does.
We know they are described in a valid theory. Their existence is substantiated by theory. That doesn't mean they (objectively) exist.No one can get close enough or find a way to analyze them effectively. We only know they exist. We know some of the properties of a black hole, but not how they relate to one another. To say "I don't believe in black holes because I don't understand them" is asanine.
Besides, I do understand how black holes work.