You’re only half right here. Simulate Physics only needs to be enabled on one of the meshes involved in the collision for OnHit to register. Furthermore, Simulate Physics doesn’t even need to be enabled for the actor you’re binding your OnHit function in.
I.e. you have a Pawn. You’re binding your OnHit function to OnComponentHit because you want this Pawn to register hit events. Simulate Physics does not need to be enabled on the Pawn, but any actors you want registering hits on this Pawn will need to Simulate Physics. Or vice versa.