I am sorry work rules have deteriorated to such a low at the sandpit.
Unless you are single, my first question would be:
What does the family think?
My buddies over there had encouraged me to join, but did not because the family vetoed it...
If I were over 55, I would suck it up and stay for 5 years.
Otherwise I do not see any reason to remain unhappy.
Money is not everything.
As for career progression, hard to match the 777 left seat.
Do you think you could find a US base which you could make your home as in Dubai?