There are per-nation limits on the number of green card holders that can become citizens every year. Maybe they want to be citizens, but aren't allowed to be?

Meanwhile, a lawyer friend of mine had to advise a client of his not to go home to visit his dying father, because he might not be allowed back in. He's lived in the US for twenty years. He owns a business that employs six US citizens. He won't get to see his father again, and a father won't get to see his eldest son on his deathbed.

So yeah, be smug. Enjoy that.