My best friend of several years has BPD so she suffers from some severe insecurities. She noticed that although some her of medications prevented from getting any pleasure from sex, the validation felt good. She said that it felt nice that her partner thought she was attractive enough for sex. After they separated, my friend is now regularly hooking up with anyone she can find, because she rationalizes that if they have sex it means shes pretty.
I told her I don't think this is a healthy way to seek validation, but she really doesnt care.

Is there anything wrong with her behavior or am I in the wrong? What are some better ways to deal with insecurities and find validation? How can I better explain to her that this might not be a healthy pattern?