You had me until the last paragraph. If "smugly" insisting X would make them dig in their heels, what are we supposed to do? Say "Oh of course it's totally in your rights, please send your unvaccinated children to the same school my kids go to"? Because I don't think it will change their minds either.
What happened to "personal responsibility" that these people like so much? If the whole country tells these people to get vaccinated, they don't, and they die, then I don't think I should be held responsible for being smug, or snarky, or whatever.