It's very easy to get caught up in what feel like large numbers until you actually look into it. 100Kt sounds big. And if it was per individual. It would be. But it's spread across 80000 people.
Many of us will produce just as much emissions on our own typical holiday. If not more.
Stop worrying about the small numbers. Global emissions are in the region of 37Gt per year. Burning man isn't perfect, it has issues. But worrying about it's 100Kt of Co2 is a rounding error. 2/?.
Worry about the big things. Concrete production (~6% global emissions), steel production (~8% global emissions), ground transport (~17% global emissions), building heat/cooling/lighting/ventilation (~25% global emissions). These are big things that have a far greater impact on the planet. Focus on fixing those. Not fighting each other over an annual holiday. 3/3.