Exhaustion, and family committments are the main reasons I have seen in supporters' email. For the ordinary fighter, Site Fights is not a supportive environment. Fighters must learn accidentally or through a mentor about Vote Exchange. Fighters expend twenty hours a week unpaid labor, and when their campaigns end, they have nothing. There are no messages in a mailing list archives, or structures like those built on multi-user real time games and no messages on a web board or in Usenet.
Defeated fighters vanish without a trace.
Rarely does so much labor yield so few results. In addition, Site Fights staff routinely lie to fighters. The ten point scoring system leaves you with no idea of how many votes you really have and how many you need. Teams appear and disappear with players informed only after the fact. Quite frankly, Site Fights are exploitive and you deserve better.