They must be out of their friggin' mind...
I wonder how long it'll take them to be crying for their old jobs back?
I don't see any problem with what these two people are doing. Years later at retirement age, would you want to look back and wish you HAD done something to realize your dream to fly, instead of baulking at the massive paycut? I understand there is a large opportunity cost involved in making a leap like that but if you think about it - there is an even larger opportunity cost if you choose to give up your passion.
I don't know Chang and Francis personally but judging from where they were in life before they chose to make a career change, I'd say it would be stupid to assume they were totally uninformed about what they were getting themselves into. You don't become an investment banker or doctor without a decent amount of common sense and foresight.