You ever bang a chick who just laid there? A "dead fish" lay is the absolute worst most boring lay I can imagine. And like I said, the way they look and the money he brings in they could have very easily found willing chicks to have a threesome with. Hell they probably could have found chicks that would be willing to take the drugs and let them bang her while she was out after she was comfortable with them or if they paid her enough. Having video proof that they didn't go beyond her boundaries and she'd let them keep doing it although I'm sure she'd want some awake loving too unless it was just a fully paid gig.
Not to mention these women were voluntarily going back to their apartment with them which generally means they were already down for some lovin. Man, some people are into some seriously freaky shit. What is scary is that two people were into the same crazy freaky "drugging and raping women most of whom were willing to bang them already" shit and they somehow found each other. It's not like you can exactly take a Craigslist ad for that.