Help me understand gratuities!

I just came off a cruise with my mum - 12 nights. We shared a cabin, and some nights she was in bed before the room steward even came to do the turndown service (she’s 80, it is what it is).

We only ate at places included in the anytime dining package, and had drinks that were included in the classic drinks package. There were some things (like room service) that we understood had a 20% gratuity added on. No problem. We also happily paid the 18 USD/day each for additional/standard gratuities.

But - we didn’t tip extra for anything. We treated all the staff respectfully, and many thanked us for being kind and making their day at various points in the journey. I gave written (individual) feedback on the handful of staff that made the trip memorable for various reasons.

But all these tipping threads have me curious so I did a quick calculation - on a 12-night cruise, standard gratuities come to 216 USD/pp for the trip. If we assume 90% of the passengers pay that, on our cruise that would be 486,000 USD in gratuities each day - or just over 5.8 million USD in gratuities for the full cruise.

A total of 1000 crew members were on our cruise, so that’s roughly 5800 USD in gratuities per crew member. I’d be very interested to hear from a crew member how much of that they actually see in their paycheck - because simple math puts it at just over 480 USD/day per crew member. Even if 50% goes to Celebrity, that’s still 240 USD/day. On top of the salary.

I feel like that is sufficient. Even knowing how incredibly hard crew members work.

Am I nuts?