I don't think helmets, seat belts, no smoking, etc. are just for the good of the user. There are medical and other costs associated with individual behaviors that impact everyone.
And yes, the reasons for a mask are completely lost on some people.
Those who believe their personal choices don't have an impact on others would be a lot more believable if they would irrevocably give up their right to bring a lawsuit if they suffer personal injury due to the actions of someone else.
If we knew what it was we were doing, it wouldn't be called research, would it?
