2. Not being loyal to an alliance
The benefits of a few select frequent flier programs speak for themselves (better seats, first boarding groups, no luggage check-in fees), and travelers also get better service, thanks to their loyalty. It's tit-for-tat backscratching. When the weather up north goes south, members are the last to be bumped, the first to be helped, and if you become super elite with a particular airline you'll have access to extreme perks (like Ferrari rides between Delta terminals in Atlanta, private VIP security and lounges on British Air in London, and more).