Well, at some point in time, everyone was once so young that everyone else in the world was older than them.
If you're female it looks like the oldest living person title is typically held for around a year[1]. Lets say that means 120 currently living people can hold the title, that gives you a 1 in 29 million[2] chance. Which feels far more likely than I would have intuitively guessed.
[1] https://en.wikipedia.org/wiki/Oldest_people#Chronological_li... [2] Or half the odds of a given ticket winning the lottery