It's comfort food, that's what. When a writer is actively querying and, therefore, facing rejection every week, there's got to be something good happening to keep her going. (I know, some writers are him, but I'm a her and I'm writing this.) :)
Of course, it doesn't have to be chocolate, but there has to be a reward for all that punishment and drudgery. The results aren't likely to be seen for years, so a gal has to keep going somehow. I do it with chocolate. My reward for sending out five queries a week is an extra two squares of my daily dark chocolate. Regular daily dose on non-querying days is two squares, so this is double!
It's enough to keep me sending them out. Well, that and the prospect of representation!
(I just got my five out today, so I'm heading for the kitchen cupboard.)