It makes no sense to only look at the risk of myocarditis. What you really want to know is how likely people in your age group and with similar predispositions

It makes no sense to only look at the risk of myocarditis. What you really want to know is how likely people in your age group and with similar predispositions are going to have serious health problems or die (i) if they are vaccinated and boostered and are exposed to SARS-CoV-2 and (ii) if they are not vaccinated and are exposed to SARRS-CoV-2. The tricky part is the "exposed to" - if you interpret this as a symptomatic breakthrough infection, then you'll bias the study a little bit against vaccination because it seems likely that fully vaccinated people who get breakthrough cases of Covid have previously undiscovered health deficiencies in contrast to those who are vaccinated, exposed to the virus and do not show any symptoms. (I'm talking about a statistical tendency, of course, not all of those people.) So in the end the most interesting data is still how many vaccinated get serious health problems or die versus how many unvaccinated get serious health problems or die in a time and place where both groups are likely to be exposed to the virus. If the group is large enough and randomly selected, then this should be fairly indicative. Of course, the meaning of "serious" needs to be defined and quantified. AFAIK, myocarditis can be treated very well when its diagnosed, that alone makes the focus on it strange. Maybe the lesson to draw from the debate is that patients should be informed better so they can identify symptoms of myocarditis and seek medical help early. Just an idea...