Who Was The Audience?

By now, you've probably seen the story of the four blacks in Chicago who kidnapped and tortured a white, mentally disabled man, screaming racial epithets at him as they did so. The event was livestreamed to Facebook by one of the perpetrators. There have been plenty of stories and analysis of the event, but there's one question I haven't seen asked or answered.

Who was the intended audience of the video? You don't livestream a video like this to your Facebook peeps thinking they're going to hate it, you put things on Facebook expecting your friends will eat it up. From the story linked above comes this tidbit.

The suspects can be heard saying they want the video to go viral.

The four abusers look to me like the classic tip of the iceberg. Yes, you saw them and they've been arrested, but there was a large audience behind them you don't see. How did that audience give these four the sense that this was going to get rave reviews?