There’s a group of fans in almost every endeavor who go a bit beyond the norm. Remember, “fan” is derived from “fanatic”, so that’s already a pretty good starting point.
Still, there are always those who go above and beyond – say, the baseball fans who memorize individual player statistics (“Don’t pinch-hit Sanders! He can’t hit a leftie after 6pm if it’s more than 76 degrees and the roof is open!”), the music fans who know who all the people in the song really are (“Sexy Sadie” was the Maharishi), the fans who know where their idols live (“stalkers.”)
So, it really shouldn’t have surprised me that the same applies to cruises. Now, you would think that you simply chose a cruise, you paid your money and you sailed somewhere, and that was the end of it. Rookie mistake.
The first group are the frequent sailors (like frequent fliers) who can tell you the best cabins on a specific ship, which dishes to avoid in which restaurant, and what weeks will have the least kids. They know the T&Cs and how to work the loopholes. They know the day the line stopped putting chocolates on pillows, and the day the lobster went away.
Then, there are those who track the individual crew members (or befriend them on social media) and book cruises based on who the butler is that week. These people answer a question like “Does anyone know when Julie is back from vacation?” with “Let me call  her and check” or “When we had dinner last week, she said she had two weeks of vacation left.”
There are ship collectors, who want to sail on every ship in a fleet. There’s actually specialists in that group, who want to sail every inaugural sailing or only Transatlantics (we met some of them, before we knew it was a thing.)
So, when I’m awake at 2:30am, watching a video feed of a new ship “floating out” into open water for the first time, I’m a little embarrassed. Just knowing that “floating out” is a thing is pretty bad, but knowing how to watch it (and then thinking about going to see one in person some day) is a bit troubling. But at least I’m not alone.