Fear spreads more easily than confidence, and roots itself very deeply, so if you are inclined to anxiety and paranoia the anti-vaxxers know exactly what buttons to push.
It continues to amaze me, though, that fear of the vaccine is greater than fear of the virus.
Maybe this boils down to an emotion that vaccines are "unnatural" and diseases are "natural" and, with any luck, sort themselves out if we just keep eating garlic, etc?
Clinging to the idea that Nature is our friend gets us into all sorts of trouble. To me, refusing the vaccine is a bit like hiking the Scottish mountains on a bright spring day without packing any warm clothing.
Science is hard to understand nowadays, and people are reading and interpreting information that was not written with the lay person in mind. Plus, there is so much information out there (with journals making COVID-related content free, and expediting publication) that it's become a bit like quoting the Bible: you can dip into the literature at random to support almost any statement you like. Especially if you don't take the trouble to read the whole article, or lack the scientific/statistical training to understand it.