> There are 349 million people in the US, so the number of arsonists is 0.0001% of the general population. The number of firefighters that are arsonists (100/65,795) is 0.0015%, so I suppose it's slightly higher that the general population.

You comparing arsonists/pop with firefighter-arsonists/arsonists. That’s the wrong comparison. You should be comparing arsonists/pop with firefighter-arsonists/firefighters. Or firefighters/pop with firefighter-arsonists/arsonists.

(On top of that, mixing numbers from different sources can be problematic. For example, how are repeat convictions treated in the different sources? Who counts as a firefighter?)