Or be a psychopath - no drugs needed
Brett Collins was allegedly in on this, wasn´t it his suggestion? Then he too is a psychopath. And Julie, if Jeremy is indeed guilty, then she knew more than she lets on, it is clear, so she is a psychopath too. Three psychopaths.
I think a logical conclusion is that they lived in a drug induced fantasy world, but of course I could be wrong, just speculating because the whole thing is so outlandish.