Halloween approaches and all around us is evidence that some of the world is obtuse to the experience of others. At least, as a trauma therapist, that's what I see when the ghosts and goblins start decorating homes around mine. Research shows that for some lucky folks, the experience of a "fright" in a safe environment (such as a movie theater or haunted house) causes a pleasurable release in dopamine and a sense of joyous thrill. However, this pleasurable reaction is often NOT the case for some:
young children (if they are too young to properly determine if a threat is real or pretend),
some trauma survivors,
some people with panic disorders, or
for highly-sensitive persons (HSPs).
Instead, a "fright" may trigger a response in the brain that feels rather unpleasant and much like past experiences of real terror.
An analogy for "horror" material, like frightening movies or haunted houses, can be found in spicy peppers. Some mouths have fewer taste buds and experience a pleasurable sensation in response to spicy peppers, while other mouths have more sensitivity to peppers, and the same pepper may feel exquisitely painful and unpleasant. Similarly, some people have a more intense and unpleasant physiological reaction to scary stuff than others.
Just as you might not serve ghost peppers at a community picnic (even if you personally love them), please extend the same courtesy to your community at Halloween and be mindful that for many people, gory or startling content triggers very unpleasant physiological reactions. Onlookers amusement at someone's unpleasant physiological reaction and suffering seems rather cruel and inhumane. Consider giving Halloween guests a heads up about frightening surprises, so they can decide for themselves if they want to participate or excuse themselves, just like you might give fair warning if you decided to serve ghost peppers to dinner guests. If there are children around, make sure each child feels safe and is only given small doses of fright they can handle, as early childhood experiences of too-much-fright can rob that child forevermore of the ability to experience the pleasurable side of fright-seeking.
Best wishes for a happy and not-too-scary (or spicy) Halloween!