I believe BPD (or a borderline personality, because personalities are really too complex to use such a categorical, syndromal approach, though possibly least so for BPD) is a rather good way to balance the two approaches to risk (and fear) and acceptance.

In a way, it integrates parts of BP and SZ in one's personality and thereby creates a more flexible approach to one's problems: being attracted by the challenge (of limited chances/opportunities) but having/using some emotional repulsion or detachment, some emotional distancing, some acceptance of one's inclinations and using them instead of fearing them.

Basically, it's doing things more deliberately to prevent it happening with less deliberation and more severity. More controlled release and exposure, mostly to control fear, like BP and SZ, but, again, more deliberate and to prevent worse escalation, undercutting BP and SZ, more or less neutralising one or the other or a combination.

I believe one could be very much worse off without it. But it's not necessarily ideal. I believe one should use it more consciously and in many ways, differently. Suppression however, I believe to be far worse.