are medically vulnerable and need others to mask around them +
live with such people +
would rather not to get Covid for no good reason and see masks as a small price to pay for a large reduction in risk
. . . is larger than a lot of people think.
I make masking decisions based on indoor ventilation - yes, I carry my CO2 monitor around - combined with Covid wastewater levels. But separately I'd be happy to mask at an event to help others.