Honestly, I think that any mental health diagnosis is serious. BPD can especially be serious due to the self harming tendencies and the possibility for suicide attempts/completions. Not only is that a problem, but BPD really isolates you from the rest of the world at times.

All that said, please do not be afraid of having a diagnosis. See it as an opportunity to know what is wrong with you and a way to work through it. Best of luck!