I'd be willing to bet that there are far more people who voluntarily make porn than people who voluntarily work on cocoa farms in Western Africa. Not that the existence of other industries where slavery and abuse are more prevalent make those problems in the porn industry any better, but at the very least a lot of work has been done to limit the amount of abuse in the adult entertainment industry and there are a lot of places where people who are being abused can find help and support, especially here in the US. You're more likely to be supporting slavery and abuse buying a Hershey's Bar or an iphone than by watching a video on pornhub.

Find chocolate that doesn't involve slave labor at some point in it's production and then say that again.