I think GM's can be very under appreciated for the work they do.
After leading a PvP Guild/Alliance for months I will say it was probably one of the most stressful and work intensive periods I've had in ESO. I would spend a lot of my time at work on our forums, WhatsApp or Skype trying to organise content and sort squabbles.
That said, it's also a very rewarding job to see your work come together and enjoy the happy comments from your members who had content that evening because of your work.
https://www.youtube.com/watch?v=M5QGkOGZubQ