Hidden variables are abstractions used to render Quantum Mechanics a deterministic theory, justifying (and in turn being justified by) Bell and Kochen–Specker's unsolved theorems.
Those who defend hidden variables claim that those theorems that would have gone unsolved without hidden variables, are in turn proof of the existence of hidden variables.
This is a ridiculous statement, comparable to the following analogy: suppose there is a theory that asserts that all animals with wings fly; such a theory would be wrong when assessing birds such as penguins and ostriches. Now imagine a group of scientists hypothesising a hidden variable that does not allow such birds to fly... such a group of mad scientists could always assert the fact that penguins and ostriches do not fly as proof of the existence of their hidden variable.
Science is wonderful, indispensable, and fascinating. We all owe so much to science, but at times, those who perform science, i.e., scientists, should be humbler and accept their own limitations.