The Trouble with Fellowship Applications

Everytime I modify my master statement for a different fellowship, I always run into the same question that causes me a serious amount of existential angst. Why am I doing what I'm doing? Of course I can point to big frickin' holes in the scholarship that I'm filling but that's not the real reason why I'm writing my dissertation. I'm writing this particular dissertation because I'd like a doctorate. It's a graduation requirement, you see. I don't think that that's the answer a selection committee is looking for, however.