They aren't just repeating the mantra that was pre-planned for the day when, inevitably, they would get Covid and have the excellent odds of getting over it and discover they could: They truly believe it because of the scare campaign! Think about it. Media hypnotized previously sensible people into believing that the most deadly disease ever was OVERWHELMING the world. It was a masterful advertising campaign. After that, the plebs started looking for things to confirm this bias. Odds favor their knowing someone who died of it, as they were told: the personal connection will help convince them they are also in danger. The illusion is reinforced with changed definitions, obfuscated data, media reports, a useless test that was the defining mark.

After a few months of this, it's understandable many would be ready to embrace a vaccine. The vaccine makers know that most of their customers will end up infected sooner or later. They plant this new bias, "it would have been worse without the vaccine." But this is not only unprovable, it reinforces their faith in the vaccine when their illness turns out to be less than they feared. So debunking the vaccine is hard without also reforming the impression of the disease and promoting treatment instead.