I think they have the right to use it to reclaim it the same way we use the n-word. However, in psychology, there is no such thing as crazy. Either someone has a specific mental illness or not. Their behavior is just a function of their condition. Yet, the word crazy implies that a person is not redeemable. And psychology does not believe anyone is beyond help. Even the most extreme disorders, like schizophrenia, have much better treatments these days. But if someone thinks they are crazy, they may not actively consider how they can make constructive changes. I've had friends die from addiction and mental illness. None of them thought they were savable. I think it's not the word crazy that's the problem as much as the finality that comes with it makes it dangerous.