Tesla only moved their headquarters, it was a PR move.

The people leaving California don't really want to leave, they are just being forced out by high costs. Those who have high incomes and can afford housing, like all those OpenAI employees, are staying.

OpenAI isn't looking for just another person that picked up AI on a whim, they are looking for people that are driving the field forward so that OpenAI stays at the very forefront. These sorts of people could learn quantum physics easily, and many probably have in their undergraduate (or graduate) degrees.