I thought I'd dump my research here in case this becomes big enough for an entry. If this story blows up in the next 16 hours then I'll be too far behind, so maybe someone else can work with it.
Basic background on the official site. Wall Street Journal reported financial problems with the festival in early April. Organized by rapper Ja Rule and entrepreneur Billy McFarland. The two of them were previously involved with a fishy startup. Headlining bands started cancelling right away.
/r/fyrefestival is about 70% trolling. /pol/ threads about the event reference the fake Reddit posts more than real sources.
One big story concerns flights to the location being cancelled so that empty planes can fly there and bring people back to U.S. This is all over the place but I haven't found any evidence other than this partial announcement.
Seemingly trustworthy attendees / primary sources:
The first two appear to be departing, so there's not likely to be more from them.