I used to run in a party crowd that had a LOT of burning man folks in it. There were a couple of them that had middle class incomes, maybe even leaning upper middle class. Those are usually the ones that had an art car or whatever that they sank some money into, instead of the crap that most upper middle class Americans blow their money on.
But the rest of them? They worked at restaurants, did massage therapy, teachers, etc. normal people with median or lower incomes that would forego other expenses to set aside a little a money for their annual get high in the desert trip.
Yes, there’s a bunch of elitists at the core of the event, but it’s not the majority.