From a financial perspective, I've had a lot of financial setbacks, so I'm very frugal. That's too lavish for me. And any money spent is money that isn't earning interest in an investment.
Also, the cruise itself may have problems. Annoying people there ... it's like living in a small village. Potential for gluttony - overeating, overdrinking. If you or your spouse has a weakness for gambling, you might end up becoming a degenerate gambler after 3 years with a casino on board. Just thinking of worst case scenarios ... maybe I'm paranoid.