Interesting thread.
One thing that I always keep in mind: "GS is a good deal, for sure, but this too shall end some day. Enjoy it while it lasts."
This much is certain for 100% of Global Services folks. There will come a day when they are no longer GS. Of course 1P for life if MM, but no longer at the head of the line.
And I do have a view of the back of the airplane, with about 600,000 miles in coach when I was on active duty.