That is exactly the group i would expect to do stupid things. People with graduate degrees tend to be intellectually smart but not street smart. People who are wealthy tend to grow up being shielded from the consequences of their actions.
Can you back up your claims?
Have you actually been to Burning Man?
I'd also point out that saying 50% of attendees are X doesn't really mean much. Hypothetically, If 0.1% of normal society take absurdly stupid risks, and 0.3% of burning man people take absurdly stupid risks, that would still be selecting for people who take absurd stupid risks.