You are so right about cruise lines knowing how to make a buck! My husband and I don't spend money in the casino or at the bars, but we can find many other places to get rid of lots of money. We have finally been on enough cruises that we no longer buy gobs of pictures. That was always a weakness of ours.
I know that a person doesn't have to spend a lot of money while cruising, but the temptations frequently outweigh common sense. At least in our case they do!