What happened to Nexon?

A lot of people in ALL MMO's quit (for like a day or two) because they thought that D3 was going to be stupidly fun, which it didn't really turn out to be.

So it just goes to show, for a day or two, it was something new, but once it settled down, it became no more of a threat to them than a lot of other MMO's. This is fairly normal in the gaming world though, which is why big updates are usually the only time they pay attention to how many active players they have. (and why the big patches must be strategically placed for a maximum amount.)