I disagree that BPD is the hardest to diagnose. The professionals I've talked to have all said that it's obvious to them when someone has it.

I think it's the hardest for people to accept their diagnosis, though. They fight it tooth and nail and try to come up with any other possibility.

Your point about "traits" is a good one to remember. Traits are basically coping mechanisms that become habit. One can change their habits, and new coping mechanisms can be learned.

This is the sixth time I've posted this. I wonder how long it will take me to delete it this time...