I think because it’s a pretty gross mischaracterization of the demographic? Usually hyperbole is used for effect to more emphatically illustrate a generally true or accepted point.
The number of Americans who use nightly sleep aids is extremely low. Like, a vast vast majority of people never take them. I don’t know anyone who regularly takes them, and honestly I don’t know many who take them even occasionally.
So this meme uses hyperbole to drive home the idea that Americans have a pill problem regarding sleep aids and no one in Europe does. I have no idea how the numbers shake out in Europe but I can say in America it is not as characterized. So it’s less hyperbole (exaggeration of a fact) and more like a lie.