I did google to see if this was a common break point, and while I didn't exhaustively review Google images, most of the ones I saw were like you said - broken 2/3rds of the way up the stylus (which suggests someone sat on it, maybe?), not at the end.
I wouldn't classify my use of the stylus as extreme or "heavy use." A few times a day, jotting down a quick note. It hasn't been treated roughly, and the rest of the stylus is in very good condition.
When you look really closely, it looks like the plastic(?) shaft of the stylus has fractured right where the clicky button joins the rest of the stylus. If I was endlessly pulling it out and pushing it in every day, then maybe that placed undue stress on that joint. But I would characterise my use of the stylus as "light" to "moderate".