Nobody in their upper 20s decides to become a doctor just to pull somebody else's chain unless she has serious psychological problems. Med school is a lot of time and expense just to get a rise out of your sister. If big sister wasn't equally screwed up, she'd realize there is absolutely no need to confront her. Even if she somehow gets into med school and makes it through, she'll be starting out deep in debt at close to 40, while big sis will have an established practice and be looking at vacation homes.