Transformation of pain into pleasure
One of the difficulties non-BDSM folk have with understanding BDSM is the transformation of pain into pleasure.
Nicola Abel-Hirsch wrote about the difference between how pain can be processed by someone as an end in itself, compared to how pain can instead be used as a gateway to somewhere else. This encapsulates the difference between true masochism and what goes on in BDSM.
Indeed, when the outcome is the satisfaction of one or more of the typical BDSM motivations, the pain itself may be effectively as insignificant as a mosquito bite (or even less). The satisfaction of the wants or needs will instead override the pain and be experienced as pleasure.