These things are very much, in my experience more about trust than the person's understanding of science. Obviously there is a mix here, and some people simply don't understand the statistics being put forward. But I think in most cases it begins with mistrust of the source of those stats. The issue with myocarditis wasn't that they didn't understand physicians were saying that the risks for it with Covid were worse than from the vaccines, it is that they didn't trust the numbers they were given (and they were also wary because the vaccine was new and were worried about unknown long term effects). Pharmaceutical companies downplay side effects all the time. For example we were told that the new opioids were non-addictive for a while (even though the opposite was true). And they were downplaying myocarditis and pericarditis as well emphasizing they were all mild cases (which might be true but those are still very serious illnesses, I have had pericarditis and isn't a joke). I think if they had treated the myocarditis issue more gravely and less glibly, that would have helped them secure trust in people who were nervous (instead they took a 'don't worry your pretty little head' approach). There has been decades long mistrust created by these companies. Now I am not saying the people who draw these conclusions are right. Like I said I got the vaccine (and I believe it prevented me from having severe COVID when I first caught Covid). But if we just paint these folks as idiots who don't know science, you aren't going to ever convince them. And let's be honest many of us who believe in the vaccines are just as scientifically illiterate.