Take a look at a map. Burning man is about two miles from the edge of the lake bed and 3-4 miles from a, probably unpaved, road.
1) I wouldn't be at such an event in the first place but if I was…
2) Put on good shoes/boots, jeans, warm shirt, etc. and slog your ass out of there. Once you are away from where the people are the ground is going to firm up somewhat since it isn't getting tore up by all the idiots. Once you are off the lake bed it will be fine. Once on the road you may be tired and your feet may hurt but you won't have trouble walking. Bottom line, like in Maui, those that take care of themselves are the ones that make it out. Those that say "We're all in this together, etc. etc" often don't.
3) If they tell you that you can't leave because it is against the rules I would reply, "Oh, well alright" And then sneak my way out ASAP.
This episode just proves that the hipster lifestyle can only be sustained if there is somebody else taking care of keeping reality at bay.
Okay, maybe I'm an unsympathetic asshole, but then I didn't take the Vaxx either, for much the same reasons. Time for these idiots to get their comeuppance