When I was young, my dad once told me a joke:
A wolf comes across a rabbit typing away with abandon. The wolf, curious, asks the rabbit what it is typing. “My dissertation,” the rabbit says. “It’s about how rabbits kill wolves.”
“Rabbits don’t kill wolves,” the wolf says. “Wolves eat rabbits.”
“No, rabbits kill wolves. Come in to my den, I’ll show you.”
So they go into the den, the wolf sure he’s about to have a very easy meal.
Inside the den, a lion waits. He kills the wolf and starts eating him. While he’s eating, the rabbit goes back outside and continues work on the dissertation.
The moral of the story: it doesn’t matter what your dissertation is about; all that matters is who your adviser is.