This is an interesting thread.
As someone who was basically browbeaten by his newly minted historical buddies into going to a convention, and putting on a game, I have found that I actually prefer running games to actually playing them, as it fulfills my need to show off the pretties I have been working on all year to other people. In the last 5 years I have added demoing a game as part of the participation game (Pulp Alley) because my love of the rules tells me I should show other people why they should play the set of rules.
I have never gotten compensation - hell, I tend to take post apoc, fantasy pirate, and VSF games to a primarily historical convention (Enfilade in Washington, USA) - sometimes I have had the feeling I didn't get best of period because they didn't want to award the "sci-fi game" above the historical games - but that doesn't mean all that much to me. I am more interested in ending a game and having everyone around the table smiling because they enjoyed it, and got to see my collection in use.
We have a couple of new cons trying to start, and I am participating in them as well, for the same reason.