I worked out on a recent Danube river cruise that it was on a par per night & the food etc far better than our local care home where my MIL stayed.
My daughter who is an opera singer used to go on opera based cruises where they performed and ran amateur courses etc. They always had several passengers who would be onboard a ship for over a year claiming it was far better value and more fun than the care home option. They even had some passengers who clearly had Alzheimer's who had been placed there by children needing a break. They also always had spare cabins for the passengers who died during the cruise! Nick