First off, any recompense in any currency; be it social, financial, material, or emotional, is/should be directly in relation to the amount of effort said 'bullet-swallower' puts forth. I'm a little surprised this has not come up.
If the GM is a figurehead using premade modules on a bought campaign with a RAW bought game, that is very different that the GM who has a thousand page wiki about his homebrew world and his own ruleset. The Gm who puts an hour of prep per session should expect a different return than the GM who puts five hours of work into every session.
Secondly, the social aspect of the game comes into play as well. Is there a huge history of shared play, or is this a new campaign? What is the emotional investiture in the characters? Are the sessions social events with wine, dinner, and spouses coming along to do quiet busywork and the whole group being friends outside of gaming, or is a coke and pizza session with people who barely know each other?
Thirdly; how invested are the players in the shared creation of the game? DO they write long backstories and ties stuff in to the GMs background work, helping him flesh out areas and creating a web of contiguity; or do we have Bob II the fighter?
As backstory, I have been paid a few times back after college, and there was a full decade where one of my groups paid all my travel expenses, since I was living a few states away from that group.