There's a YouTube video that talks about how valuable the major US airlines reward program is. The market cap of each airline is less than the value of each airline's reward program at the time the video was made.

I recall Apple was valued in a similar manner back in the late 1990s. Their market cap was barely more than cash on hand. Talk about missed investing opportunities...

Not that I'm saying airlines are the next AAPL.

edit - here's the video - "How Airlines Quietly Became Banks" - https://www.youtube.com/watch?v=ggUduBmvQ_4