So I took a shot at this myself.
Myocarditis from the vaccine.
DanM's link says there are 12.6 cases of myocarditis for every million doses of the vaccine.
That's .00126%.
If you get Pfizer or Moderna, you need two shots, so we double the rate to .00252%.
Myocarditis from the virus itself.
A study of 1597 college athletes showed that 2.3% had clinical and subclinical myocarditis after having had a Covid infection.
But not everyone gets Covid, even if you are unvaccinated. So you have to factor that in.
There have been about 33 million confirmed cases of Covid in this country. The total number of cases is higher, since there have been plenty of cases that were never tested. But I'll be conservative here and just use the 33 million number, which is roughly 10% of the population.
If you have a 10% chance of getting Covid, and if you get Covid you have a 2.3% chance of getting myocarditis, your chance of getting myocarditis from Covid is .23%.
Which gives you the better odds?
The .23% chance if you remain unvaccinated is higher than the .00252% chance if you get vaccinated.
In fact, it looks like your chance of skipping the vaccine and getting myocarditis from Covid is close to 100 times greater than the chance of getting myocarditis from the vaccine. Mathematically, it seems like a no brainer.
https://jamanetwork.com/journals/jamacardiology/fullarticle/2780548