It would be interesting to show FlyerTalk to a person who has never flown and let them read the Frequent Flier Forums about getting points to fly, Lounge Access, Inflight Entertainment at your seat, Requesting a Special Meal, Seat Assignments etc. I wonder what their reactions would be.
I know a handful of people who have never flown but the people I speak to fly.
I am fortunate to be able to fly more than once a year and make as many international trips as I do. Perhaps the non flying couple does not know you can get good deals by flying or are afraid to fly.