One could at least try to estimate their personal cost of wearing a mask by considering the following:
Suppose my chance of getting sick at EAG was 0%. How much would someone have to pay me to wear a mask?
If we're talking about the entire conference, I think I'd need to be paid at least a few hundred dollars.
In concrete, practical terms, how do you envision "most of EA" being funded by governments? At least in the US context, this is very hard for me to imagine, as it runs counter to a lot of my understanding of the political economy of taxation and government spending.