I don't think we have any reason to believe that this is an unearned luxury lavished on a lucky elderly couple. It appears more likely that this is their own money, saved and invested over their lifetime, and their's to spend how they wish. Furthermore, advanced age is no reason to cast someone off to a bland waiting room. It's not healthy for a society to consider somebody's value limited to their future contribution potential. I'm happy to contribute economically to present-day's elderly folks, not only for my own attachment to someone, but for the social contract that I, too, will be old, and I doubt I'll suddenly just want to stand in the corner.
Even if we take your claim about society being better off if the 14k goes to education (which is some major hand waving), how would you suggest transferring this?
Unless it's completely by choice, congratulations. You've now created no incentive for people working towards retirement to save enough to spend 14k per month. Now, instead of getting that productivity earlier in life and the 14k going to support a cruise ship business, you'll have people willing to just rest with what they've got.
I think there are better ways to prop up education (some having nothing to do with $). No need to shame the elderly who have worked a lifetime and now get to kick back and enjoy it for a little while.
In the alternative, where they're paying $2.5k/month, the other $9.5k/month is going to stay in their investment accounts, and when they eventually die, if they have a large enough estate, it'll be subject to the estate tax and society could use it for education or whatever, but more likely it'll just pass to their heirs, which helps the heirs, but doesn't help society that much.
I would certainly hope so, considering for 14,000/month you can live on an actual cruise ship with money left over for entertainment and a few other things.
It also pains me to see such luxury spent on the elderly. While you may have a personal attachment to them, the rest of society would do much better with that money spent to educate and help the new generations.