I get that about the costs in Cali – but that doesn’t mean lots of people in Cali are automatically poor or can claim not to be well-to-do. In fact, I’d say that’s a dangerous idea, because rich in California can also tend to be richer than elsewhere, for the same reasons you cited.
Is it correct to say the data in this census was self-reported?
Edit: also, do you happen to know the average cost of a ticket to Burning Man? Googling produces weird results due to a strange pricing scheme.