Um...that shit totally happens.
It is absolutely not farfetched. Even movies like Eyes Wide Shut that portray it pretty extravagantly aren't too farfetched. I've actually seen one of these things in action. A friend invited me to a party, and I had known she was a swinger...I arrive at the club, and people are looking at me weird as all hell (I later found out it's because I wasn't either naked and/or wearing some weird shit..not to say that people were all 'Eyes-Wide-Shutting-it', but some people did have more just funny/halloween-y costumes to cover their face..mostly people were just naked/very close to it)...and when I get into the main room, the girl that invited me is getting fucked by about four different guys in a room with all glass and there's about 150-200 people in this big ass room, watching, playing with each other, some other people fucking. It was insane. I stayed for about two minutes and yelled her name, gave her a thumbs up, and then bailed out of that mofo like a fire was lit under my ass.
I'm down with some freaky shit in the bedroom now and again, but holy hell. So yes, definitely not farfetched. Does it happen everyday like a normal thing? Probably not. But believe you me, this crazy shit does indeed happen; and I'm sure moreso with the insane rich people. As in...they're insane AND rich/wealthy.
Ed: Oh and I should mention this was in Los Angeles.