Why do some people get appendicitis while others don't?

Appendicitis: The cause of appendicitis isn't always clear. Sometimes appendicitis can occur as a result of an obstruction such as food waste or a hard piece of stool which can block the opening of the cavity that runs the length of your appendix.Appendicitis may also follow an infection, such as a gastrointestinal viral infection, or it may result from other types of inflammation.

Gene/ food: Most people do not get appendicitis. Some dietary factors compounded with genetic predisposition plays role. No clear causation.

the lumen of the: Appendix becomes obstructed which then sets the process for appendicitis to occur.

Not sure: You need to have a fecolith ( hard stool stuck in the appendix) to get acut appendicitis. Not sure why some do and others do not.