Fun is real, and it’s vital. It can even be spiritual, as long as you don’t get attached to it and forget that it will — eventually — end. In a world desperately attached to fun, Burners have found a way to make their fun a little more fulfilling: by throwing in some death practice. They do it by bringing their fun out to an inhospitably extreme environment, and then they try to see how much fun they can still have without dying.
It’s precisely that experience of extremes which leads to what might somewhat ironically be called the real spirituality of Burning Man. It’s a spirituality of instinctual responses, not religious rules.