So I noticed that you can select the LAST page of the achievements leaderboard, and see how many players are actually out there (57755, at the moment). Then I thought of my habit of compulsively adding everyone I meet as a friend (and who knows how many I have now). And eventually... the realization hit me!
I. Could. Befriend. Each. One. From. There.
Or almost. In fact, you could click on each leaderboard entry, go on their profile page and click the "add as a friend" button. 57755 times. How much of an achievement does it sound to you?
(Seriously, I won't do that. But it's the sort of deranged achievement one would expect from the people who invented some of the badges out there...)