Well, the hobby IS part of commercial sex trade. So is porn, stripping, camming and any sort of fetish or FBSM work.  Any endeavor that involves exchanging sexual services for money, paid directly or indirectly, is part of the commercial sex industry.

Now, not everyone who works in the commercial sex industry is trafficked. In my personal experiences, most women get involved in it willingly and know exactly what they are doing.  Still, human trafficking does exist and being aware of it is one way to keep from getting involved in it.