Looks like Burning Man pays about $2M to BLM for the event out of their revenues of $12M. So it's like 20% of revenue, not "most" of the revenue. Also, much of the cleaning, setup etc is done by volunteers if I understand correctly.
In 2016, BRC paid BLM $2,199,959 to cover the costs of staffing the weeklong arts and lifestyle festival, which also has a set-up, breakdown, and cleanup schedule lasting more than two months. When all stages of the 2016 event were complete, including post-event inspection, the BLM had spent $2,166,127.41 on the event, leaving BRC with a refund of $33,831.59.
In 2016, BRC paid BLM $2,199,959 to cover the costs of staffing the weeklong arts and lifestyle festival, which also has a set-up, breakdown, and cleanup schedule lasting more than two months. When all stages of the 2016 event were complete, including post-event inspection, the BLM had spent $2,166,127.41 on the event, leaving BRC with a refund of $33,831.59.
https://www.blm.gov/press-release/final-cost-recovery-2016-b...