I have had this problem allot as well, very enthusiastic players who have just then dropped out of the game for some real life reason. I do however think that one of the biggest troubles is that many are seeking instant gratification. If a game is taking any time to build up, then often players will drop of, if the GM is sick for three days and can not post, then players will drop of, if the game is going a little slow for a few days, then players will drop of. I am often feeling like I do when I try to start a cow run in Diablo 2 when starting new RPGs on this site that unless things is happening at once, and constantly then players will drop of, that the problem is that many lack any patience and so games get rushed and then they get less interested and you end up in a damned if you do, damned if you don't kind of scenario where if you do not rush the game then your players will get tired of waiting for the good things to happen in a few days, and if you do rush your game the storyline ends up less interesting and the players will leave anyway.Roleplays I've run have died mainly not because of lack of interest at all. I've had a wildly enthusiastic and excited player group, eagerly posting characters and a lot of back-and-forth chat in the OOC about the upcoming game, the game universe, and whatever else they're doing... and then all at once, everything will stop abruptly because of something completely outside of the game. Usually related to school/college/uni/whatever, and then none of them will come back afterward.