This was the question posed to me this week when we were discussion particle physics and the Large Hadron Collider in our classroom by an exceptionally bright student. She followed it up with "This just seems like an enormous waste of money." I surely see her point. When you have friends at school who come from homes were there's not enough to eat or when they can't (or won't) keep the electric bill paid.
I imagine its also due (at least in part) to the idea students have that "everything that can be known, is". As a student in high school, a person who has a constant inflow of information everyday, its easy to think the world is pretty well all figured out. I would say this is not the case, nor will it ever be. That doesn't mean we shouldn't stop questioning. In fact, even if we, as scientists, think the world is all figured out, it would be a huge mistake to stop asking questions. According to Humphrey Davy: "Nothing is so dangerous to the progress of the human mind than to assume that our views of science are ultimate, that there are no mysteries in nature, that our triumphs are complete and that there are no new worlds to conquer." It is worth mentioning that Davy was the mentor of Michael Faraday, who produced the theory that electrical force and the magnetic force are the same thing. This was the first Unified Theory of Physics, which laid the groundwork for all other unification theories in Physics. So in essence, we can thank Davy for everything we know about Physics, for without his encouragement of Faraday, we might not understand physics much better than we did back in the 1800's.
I think Albert Einstein said it best: "The important thing is not to stop questioning". That is the point! That is why we do research. All of the technology we gain from particle physics research is just a bonus. The reason to do the research is for the knowledge gained.
Thanks for reading.