The reason myocarditis is underreported is because most cases are incredibly mild. So if you have a choice between a disease you have a 45% chance of catching and a 1% chance of dying of, or a vaccine with a 1 in 10,000 chance of having an adverse reaction to, with a 1 in 20,000 chance that it would be fatal, which would you rather choose?
9 billion doses have been given out! If there were serious safety concerns with vaccines, I would personally know people affected.
Of course you are incredibly unlucky if you are one of the 3000 people in the US who are seriously affected by a vaccine, but people telling me my winning lottery ticket is fake isn't an example of oppression - you want a doctor who doesn't jump to weird edge cases at first chance.
It's not that these people "don't understand the science", it's that they don't understand probability.