It's real but like most if not all behavioral disorders (not those caused by chemical imbalance in the brain) it's curable. BPD can be cured. It takes therapy. However, the problem with behavioral disorders is that patients typically don't see them as disorders, or refuse to, because it's not making them lose their minds in a literal sense or giving them disassociation or mental flashes like PTSD (also curable but not a behavioral disorder).
BPD requires the person to acknowledge there's something wrong, want to change, get therapy, still want to change, and throughout they take time discovering the root cause (typically trauma, typically child abuse, typically sexual (hence the paranoia, trouble identifying and trusting real intimacy, the extreme highs and lows, the fear of being abandoned so you destroy everything first before it can leave you, etc.) ) and processing it.
Some people get raped, have severe PTSD and overcome its effects in like 6 months with a support network (spouse, lover, friend, family basically) and good therpist. Others go mute from trauma and take years. Therapy persists even after symptoms subside and after the patient has fully processed the trauma which caused this disorder, whatever it is. Same with BPD.
But BPD is often used as an excuse to be a dick, yeah, like how crazy people use "I have a sugar imbalance" as an excuse for snapping at you. Most who recover from BPD never mention they had BPD because of the rightful stigma. That being said...