What can I do about my sister keep claiming that she's a psychopath and crazy?

My sister always says that she's crazy and a psychopath and I think it's very cringey but I don't know how to tell her that. She also says that she's crazy to her friend and her friend just tell her "you're not crazy". I think it's because one time this guy told her about the crazy-hot scale thing that Neil Patrick Harris brought up "How I met your mother". Since my sister is pretty, she keeps trying to justify that she's crazy too when she's completely normal. I tell her about how I was abused living at home, and she was the favourite child. And she tries to claim that she was abused too and probably worst than me. I was the black sheep of the family and she was the golden child, my mom literally backed her for everything. So she further tries to claim this is why she's crazy. And since she heard about the Johnny Depp-Amber Heard situation, she tries to say that she's crazy again.
What can I do about my sister keep claiming that she's a psychopath and crazy?
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