Hey - I can tell you what my supervisor and few of my friends who went to USA told me.
Yes! Waitlists are realistic. They are usually small, and being waitlisted means they want you, but due to a number of factors, they can’t admit you right away.
Sometimes, it happens that no people from waitlist get in, because everyone accepts, but I know 5 people who got in from it. Like everything else with admissions, its Russian roulette. If its any help - a friend of my got waitlisted last week, abd admitted this week.
BTW, which program is this?